Midterm STATs
Use the given categorical data to construct the relative frequency distribution. Natural births randomly selected from four hospitals in a highly populated region occurred on the days of the week (in the order of Monday through Sunday) with the frequencies 54, 65, 70, 56, 57, 43, 55. Does it appear that such births occur on the days of the week with equal frequency?
Percentage for a class=frequency for a classs/ sum of all frequencies×100% Let the frequencies be substantially different if any frequency is at least twice any other frequency. Does it appear that these births occur on the days of the week with equal frequency? Yes, it appears that births occur on the days of the week with frequencies that are about the same.
Which of the following is NOT a voluntary response sample?
Quiz scores from a college level statistics course are analyzed to determine student progress.
Listed below are the numbers of hurricanes that occurred in each year in a certain region. The data are listed in order by year. Find the range, variance, and standard deviation for the given sample data. Include appropriate units in the results. What important feature of the data is not revealed by any of the measures of variation? 7 15 8 4 16 7 20 9 4 15 11 13 10
STAT crunch = stats + summary The range of the sample data is 16 hurricanes. Part 2 The standard deviation of the sample data is 5.0hurricanes Part 3 The variance of the sample data is 25 hurricanes. Part 4 What important feature of the data is not revealed through the different measures of variation? The measures of variation reveal nothing about the pattern over time.
State whether the data described below are discrete or continuous, and explain why. The weights of dogs (in pounds) at a dog show
The data are continuous because the data can take on any value in an interval.
State whether the data described below are discrete or continuous, and explain why. The weights of dogs in pounds at a dog show
The data are continuous because the data can take on any value in an interval.
State whether the data described below are discrete or continuous, and explain why. The numbers of people that drive by a certain billboard each day
The data are discrete because the data can only take on specific values.
Identify the level of measurement of the data, and explain what is wrong with the given calculation. In a survey, the favorite sports of respondents are identified as 100 for basketball, 200 for baseball, 300 for football, and 400 for anything else. The average (mean) is calculated for 547 respondents and the result is 256.1.
The data are nominal level of measurement. What is wrong with the given calculation? Such data are not counts or measures of anything, so it makes no sense to compute their average (mean).
Determine whether the given value is a statistic or a parameter. A homeowner measured the voltage supplied to his home on 27 days of a given month, and the average (mean) value is 122.6 volts.
The given value is a statistic for the month because the data collected represent a sample.
Waiting times (in minutes) of customers in a bank where all customers enter a single waiting line and a bank where customers wait in individual lines at three different teller windows are listed below. Find the mean and median for each of the two samples, then compare the two sets of results. Single Line 6.3 6.6 6.7 6.8 6.9 7.2 7.4 7.8 7.8 7.8 Individual Lines 4.1 5.3 6.0 6.1 6.3 7.8 7.8 8.5 9.4
The mean waiting time for customers in a single line is 7.13 minutes. Part 2 The median waiting time for customers in a single line is 7.05 minutes. Part 3 The mean waiting time for customers in individual lines is 7.13minutes. Part 4 The median waiting time for customers in individual lines is 7.05 minutes. Part 5 Determine whether there is a difference between the two data sets that is not apparent from a comparison of the measures of center. If so, what is it? The times for customers in individual lines are much more varied than the times for customers in a single line.
Determine which of the four levels of measurement (nominal, ordinal, interval, ratio) is most appropriate for the data below. Jersey numbers of baseball players
The nominal level of measurement is most appropriate because the data cannot be ordered.
Assume that 500 births are randomly selected and 482 of the births are girls. Use subjective judgment to describe the number of girls as significantly high, significantly low, or neither significantly low nor significantly high.
The number of girls is significantly high.
Assume that 1200 births are randomly selected and 44 of the births are girls. Use subjective judgment to describe the number of girls as significantly high, significantly low, or neither significantly low nor significantly high.
The number of girls is significantly low.
A thief steals an ATM card and must randomly guess the correct three-digit pin code from a 7-key keypad. Repetition of digits is allowed. What is the probability of a correct guess on the first try?
The number of possible codes = 7 ^ 3 = 343 The probability that the correct code is given on the first try is 1/ 343
Determine which of the four levels of measurement (nominal, ordinal, interval, ratio) is most appropriate for the data below. Rating of novels
The ordinal level of measurement is most appropriate because the data can be ordered, but differences (obtained by subtraction) cannot be found or are meaningless.
In a certain weather forecast, the chances of a thunderstorm are stated as "1 in 18." Express the indicated degree of likelihood as a probability value between 0 and 1 inclusive.
The probability is 0.056.
Let event A=subject is telling the truth and event B=polygraph test indicates that the subject is lying. Use your own words to translate the notation P(B|A) into a verbal statement.
The probability that the polygraph indicates lying given that the subject is actually telling the truth.
Find the (a) mean, (b) median, (c) mode, and (d) midrange for the data and then (e) answer the given question. Listed below are the weights in pounds of 11 players randomly selected from the roster of a championship sports team. Are the results likely to be representative of all players in that sport's league?
The results are not likely to be representative because the championship team may not be representative of the entire league.
A defunct website listed the "average" annual income for Florida as $35,031. What is the role of the term average in statistics? Should another term be used in place of average?
The term average is not used in statistics. The term mean should be used for the result obtained by adding all of the sample values and dividing by the total number of sample values.
Use z scores to compare the given values. Based on sample data, newborn males have weights with a mean of 3240.3 g and a standard deviation of 845.9 g. Newborn females have weights with a mean of 3070.8 g and a standard deviation of 539.2 g. Who has the weight that is greater relative to the group from which they came: a male who weighs 1600 g or a female who weighs 1600 g?
The z score for the male is z=−1.94 and the z score for the female is z=−2.73. The male has the weight that is relatively greater.
If your score on your next statistics test is converted to a z score, which of these z scores would you prefer: −2.00, −1.00, 0, 1.00, 2.00? Why?
The z score of 2.00 is most preferable because it is 2.00 standard deviations above the mean and would correspond to the highest of the five different possible test scores.
A random sample of 10 subjects have weights with a standard deviation of 12.0987 kg. What is the variance of their weights? Be sure to include the appropriate units with the result.
The variance, s2, of a set of values is a measure of variation equal to the square of the standard deviation. Notice that the standard deviation of the data set is given as 11.5570 kg. Part 2 Square the standard deviation to find the variance, rounding to four decimal places. s2= (12.0987kg)2 =146.3785kg The variance of the sample data is 146.3785 kg2
When making predictions based on regression lines, which of the following is not listed as a consideration?
Use the regression line for predictions only if the data go far beyond the scope of the available sample data.
Listed below are foot lengths in inches for 11 randomly selected people taken in 1988. Find the range, variance, and standard deviation for the given sample data. Include appropriate units in the results. Are the statistics representative of the current population of all people?
Variance = ? squared Are the statistics representative of the current population of all people? Since the measurements were made in 1988, it is not necessarily representative of the population today.
Which of the following statements about correlation is true?
We say that there is a positive correlation between x and y if the x-values increase as the corresponding y-values increase.
When a man observed a sobriety checkpoint conducted by a police department, he saw 680 drivers were screened and 7 were arrested for driving while intoxicated. Based on those results, we can estimate that P(W)=0.01029, where W denotes the event of screening a driver and getting someone who is intoxicated. What does PW denote, and what is its value?
What does PW represent? PW denotes the probability of screening a driver and finding that he or she is not intoxicated. Find PW: P(W "with line over") = 1- 0.01029 PW = 0.98971
Identify which of these types of sampling is used: random, systematic, convenience, stratified, or cluster. To determine her power usage, Carolyn divides up her day into three parts: morning, afternoon, and evening. She then measures her power usage at 3 randomly selected times during each part of the day.
What type of sampling is used? Stratified
Identify the type of sampling used (random, systematic, convenience, stratified, or cluster sampling) in the situation described below. In a poll conducted by a certain research center, 1140 adults were called after their telephone numbers were randomly generated by a computer, and 81% were able to correctly identify the vice president.
Which type of sampling did the research center use? random sampling
Identify which type of sampling is used: random, systematic, convenience, stratified, or cluster. To determine customer opinion of their food quality, General Foods randomly selects 140 city blocks during a certain week and surveys all homes within the city blocks.
Which type of sampling is used? cluster
Subjects for the next presidential election poll are contacted using telephone numbers in which the last four digits are randomly selected (with replacement). Find the probability that for one such phone number, the last four digits include at least one 0.
the probability is 0.344
You are certain to get a black or a red card when selecting cards from a shuffled deck. Express the indicated degree of likelihood as a probability value between 0 and 1 inclusive.
the probability is 1
A defunct website listed the "average" annual income for Florida as $35,031. What is the role of the term average in statistics? Should another term be used in place of average?
the term average is not used in statistics. The term mean should be used for the result obtained by adding all of the sample values and dividing by the total number of sample values
Use the magnitudes (Richter scale) of the 120 earthquakes listed in the accompanying data table. Use technology to find the range, variance, and standard deviation. If another value, 7.00, is added to those listed in the data set, do the measures of variation change much?
use stat crunch Do the measures of variation change much with the extra data value? Choose the correct answer below. The ranges are more than 5 percentage points apart, the variances are more than 5 percentage points apart ,and the standard deviations are more than 5 percentage points apart, so all of them change significantly
Refer to the sample data for pre-employment drug screening shown below. If one of the subjects is randomly selected, what is the probability that the test result is a false positive? Who would suffer from a false positive result? Why?
use the relative frequency approach: P(A) = number of times A occurred / number of times the procedure was repeated P(false positive) = number of false positive test results / total number of test results
Consider a value to be significantly low if its z score less than or equal to −2 or consider a value to be significantly high if its z score is greater than or equal to 2. A test is used to assess readiness for college. In a recent year, the mean test score was 20.8 and the standard deviation was 4.6. Identify the test scores that are significantly low or significantly high.
First, use the equation for z to write an equation for the value of x that is the greatest significantly low test score. −2= x−20.8 / 4.6 x= 11.6 so, test score is significantly low if it is less than or equal to 11.6 Next, use the equation for z to write an equation for the value of x that is the least significantly high test score. 2= x - 20.8 / 4.6 x= 30.0
If we find that there is a linear correlation between the concentration of carbon dioxide in our atmosphere and the global temperature, does that indicate that changes in the concentration of carbon dioxide cause changes in the global temperature?
No. The presence of a linear correlation between two variables does not imply that one of the variables is the cause of the other variable.
Which of the following is NOT a requirement of the Permutations Rule, nPr=n!(n−r)!, for items that are all different?
Order is not taken into account (rearrangements of the same items are considered to be the same).
In a survey of consumers aged 12 and older, respondents were asked how many cell phones were in use by the household. (No two respondents were from the same household.) Among the respondents, 206 answered "none," 283 said "one," 370 said "two," 137 said "three," and 114 responded with four or more. A survey respondent is selected at random. Find the probability that his/her household has four or more cell phones in use. Is it unlikely for a household to have four or more cell phones in use? Consider an event to be unlikely if its probability is less than or equal to 0.05.
P ( four or more cell phones ) = number of respondents with four or more phones / total number of respondants
Use the following results from a test for marijuana use, which is provided by a certain drug testing company. Among 146 subjects with positive test results, there are 21 false positive results; among 155 negative results, there are 4 false negative results. If one of the test subjects is randomly selected, find the probability that the subject tested negative or did not use marijuana. (Hint: Construct a table.)
P (A or B) = P (A) + P(B) - P(A and B)
When a man observed a sobriety checkpoint conducted by a police department, he saw 689 drivers were screened and 5 were arrested for driving while intoxicated. Based on those results, we can estimate that P(W)=0.00726, where W denotes the event of screening a driver and getting someone who is intoxicated. What does PW denote, and what is its value?
P (W) denotes the probability of screening a driver and finding that he or she is not intoxicated. P(W) = 0.99274
Determine whether the underlined number is a statistic or a parameter. In a study of all 2381 professors at a college, it is found that 45% own a television.
Parameter because the value is a numerical measurement describing a characteristic of a population.
A random sample of 10 subjects have weights with a standard deviation of 11.2639 kg. What is the variance of their weights? Be sure to include the appropriate units with the result.
126.8754 kg2
A sample of 34 women is obtained, and their heights (in inches) and pulse rates (in beats per minute) are measured. The linear correlation coefficient is 0.287 and the equation of the regression line is y=18.2+0.870x, where x represents height. The mean of the 34 heights is 62.8 in and the mean of the 34 pulse rates is 75.7 beats per minute. Find the best predicted pulse rate of a woman who is 74 in tall.
75.70
For a data set of the pulse rates for a sample of adult females, the lowest pulse rate is 36 beats per minute, the mean of the listed pulse rates is x=76.0 beats per minute, and their standard deviation is s=21.8 beats per minute. a. What is the difference between the pulse rate of 36 beats per minute and the mean pulse rate of the females? b. How many standard deviations is that [the difference found in part (a)]? c. Convert the pulse rate of 36 beats per minutes to a z score. d. If we consider pulse rates that convert to z scores between −2 and 2 to be neither significantly low nor significantly high, is the pulse rate of 36 beats per minute significant?
A. In this problem, subtract the lowest pulse rate from the mean. First set up the difference. Then subtract. 76.0−36.0= 40 b. Compare the difference 40beats per minute to the standard deviation 21.8 beats per minute. 40/21.8 = 1.83 standard deviations C. find z score =-1.83 d. A value is significantly low if the z score less than or equal to −2. A value is significantly high if the z score is greater than or equal to 2. Otherwise, the value is not significant. not significant
Researchers measured the data speeds for a particular smartphone carrier at 50 airports. The highest speed measured was 74.7 Mbps. The complete list of 50 data speeds has a mean of x=17.63 Mbps and a standard deviation of s=17.67 Mbps. a. What is the difference between carrier's highest data speed and the mean of all 50 data speeds? b. How many standard deviations is that [the difference found in part (a)]? c. Convert the carrier's highest data speed to a z score. d. If we consider data speeds that convert to z scores between −2 and 2 to be neither significantly low nor significantly high, is the carrier's highest data speed significant?
A. subtract the mean from the carrier's highest data speed. 74.7 - 17.63 = 57.07 b. Compare the difference 57.07Mbps to the standard deviation 17.67Mbps. 57.07/17.67 = 3.23 c. determine whether a sample or population. Use z score equation. D. greater than 2 = significantly high
Use the data in the following table, which lists drive-thru order accuracy at popular fast food chains. Assume that orders are randomly selected from those included in the table. If one order is selected, find the probability of getting an order from Restaurant A or an order that is accurate. Are the events of selecting an order from Restaurant A and selecting an accurate order disjoint events?
Are the events of selecting an order from Restaurant A and selecting an accurate order disjoint events? The events are not disjoint because it is possible to receive an accurate order from Restaurant A.
There are 15,958,866 adults in a region. If a polling organization randomly selects 1235 adults without replacement, are the selections independent or dependent? If the selections are dependent, can they be treated as independent for the purposes of calculations?
Are the selections independent or dependent? The selections are dependent, because the selection is done without replacement. If the selections are dependent, can they be treated as independent for the purposes of calculations? Yes, because the sample size is less than 5% of the population.
In horse racing, a trifecta is a bet that the first three finishers in a race are selected, and they are selected in the correct order. Does a trifecta involve combinations or permutations? Explain.
Because the order of the first three finishers does make a difference, the trifecta involves permutations.
The blood platelet counts of a group of women have a bell-shaped distribution with a mean of 262.8 and a standard deviation of 67.5. (All units are 1000 cells/μL.) Using the empirical rule, find each approximate percentage below. a. What is the approximate percentage of women with platelet counts within 1 standard deviation of the mean, or between 195.3 and 330.3? b. What is the approximate percentage of women with platelet counts between 127.8 and 397.8?
Empirical rule for bell shaped: About 68% of all values fall within 1 standard deviation of the mean. About 95% of all values fall within 2 standard deviations of the mean. About 99.7% of all values fall within 3 standard deviations of the mean. a. Approximately 68% of women in this group have platelet counts within 1 standard deviation of the mean, or between 195.3 and 330.3. b. To find this percentage, first find how many standard deviations the values 109.6 and 432.4 lie from the mean. Notice that since 271.0−3×53.8=109.6, 109.6 is 3 standard deviations less than the mean, and since 271.0+3×53.8=432.4, 432.4 is 3 standard deviations greater than the mean. Approximately 95% of women in this group have platelet counts between 127.8 and 397.8.
Listed below are the budgets (in millions of dollars) and the gross receipts (in millions of dollars) for randomly selected movies. Answer parts a-b. Budget (x) 62 92 53 38 190 105 90 Gross (y) 60 61 50 53 574 144
Find the value of the linear correlation coefficient r. - Stat crunch - correlation
Determine whether the sampling method described below appears to be sound or is flawed. In a survey of 543 subjects, each was asked how often he or she read a book. The survey subjects were internet users who responded to a question that was posted on a news website.
It is flawed because it is a voluntary response sample.
Determine whether the sampling method described below appears to be sound or is flawed. In a survey of 686 subjects, each was asked how often he or she watched TV. The survey subjects were internet users who responded to a question that was posted on a news website.
It is flawed because it is a voluntary response sample.
Based on a poll, 60% of Internet users are more careful about personal information when using a public Wi-Fi hotspot. What is the probability that among four randomly selected Internet users, at least one is more careful about personal information when using a public Wi-Fi hotspot? How is the result affected by the additional information that the survey subjects volunteered to respond?
It is very possible that the result is not valid because the sample may not be representative of the people who use public Wi-Fi.
Twenty different statistics students are randomly selected. For each of them, their body temperature (°C) is measured and their head circumference (cm) is measured. If it is found that r=0, does that indicate that there is no association between these two variables?
No, because while there is no linear correlation, there may be a relationship that is not linear.
Listed below are the amounts (dollars) it costs for marriage proposal packages at different baseball stadiums. Find the range, variance, and standard deviation for the given sample data. Include appropriate units in the results. Are there any outliers, and are they likely to have much of an effect on the measures of variation? 39 45 45 65 70 95 95 100 175 209 265 375 400 1500 3000
STAT crunch: range = 2961 dollars Standard deviation = 799.1 dollars variance = 638,560.8 dollars2 Are there any outliers and, if so, are they likely to have much of an effect on the measures of variation? yes, the largest amounts are much higher than the rest of the data, and appear to be outliers. It is likely that these are having a large effect on the measures of variation.
When determining whether there is a correlation between two variables, one should use a ____________ to explore the data visually.
Scatterplot
Use the given data to find the equation of the regression line. Examine the scatterplot and identify a characteristic of the data that is ignored by the regression line. x 15 12 11 7 10 14 9 6 8 5 13 y 7.02 9.01 9.07 6.26 8.82 7.99 8.27 4.79 7.41 3.02 8.66
Stat crunch - regression intecept and slope ^y = intercept + slope x
Identify the type of sampling used (random, systematic, convenience, stratified, or cluster sampling) in the situation described below. A researcher selects every 190th social security number and surveys the corresponding person.
Systematic sampling
Which of the following is NOT a requirement of the Combinations Rule, nCr=n!r!(n−r)!, for items that are all different?
That order is taken into account (consider rearrangements of the same items to be different sequences).
A sample of 24 women is obtained, and their heights (in inches) and pulse rates (in beats per minute) are measured. The linear correlation coefficient is 0.276 and the equation of the regression line is y=17.8+0.860x, where x represents height. The mean of the 24 heights is 63.6 in and the mean of the 24 pulse rates is 75.3 beats per minute. Find the best predicted pulse rate of a woman who is 73 in tall.
The best predicted pulse rate of a woman who is 73 in tall is 75.30 beats per minute.
Suppose IQ scores were obtained for 20 randomly selected sets of twins.The 20 pairs of measurements yield x=103.11, y=101.85, r=0.897, and y=8.54+0.9x, where x represents the IQ score of the twin born second. Find the best predicted value of y given that the twin born second has an IQ of 90?
The best predicted value of y is 89.54.
The body temperatures of a group of healthy adults have a bell-shaped distribution with a mean of 98.19°F and a standard deviation of 0.56°F. Using the empirical rule, find each approximate percentage below. a. What is the approximate percentage of healthy adults with body temperatures within 2 standard deviations of the mean, or between 97.07°F and 99.31°F? b. What is the approximate percentage of healthy adults with body temperatures between 96.51°F and 99.87°F?
a. Approximately 95% of healthy adults in this group have body temperatures within 2standard deviations of the mean, or between 97.07°F and 99.31°F. B.Approximately 99.7% of healthy adults in this group have body temperatures between 96.51°F and 99.87°F.
Find the (a) mean, (b) median, (c) mode, and (d) midrange for the data and then (e) answer the given question. Listed below are the weights in pounds of 11 players randomly selected from the roster of a championship sports team. Are the results likely to be representative of all players in that sport's league? 272 281 255 242 263 246 271 274 263 250 274
a. Find the mean. 262.8 B. find the median 263.0 c.Find the mode. The mode(s) is(are) 263, 274 pound(s). d. Find the midrange. The midrange is 261.5261.5 pound(s). e. Are the results likely to be representative of all players in that sport's league? The results are not likely to be representative because the championship team may not be representative of the entire league.
A corporation must appoint a president, chief executive officer (CEO), chief operating officer (COO), and chief financial officer (CFO). It must also appoint a planning committee with five different members. There are 12 qualified candidates, and officers can also serve on the committee. Complete parts (a) through (c) below.
a. How many different ways can the officers be appointed? There are 11880 different ways to appoint the officers. Part 2 b. How many different ways can the committee be appointed? There are 792 different ways to appoint the committee. Part 3 c. What is the probability of randomly selecting the committee members and getting the five youngest of the qualified candidates? P(getting the five youngest of the qualified candidates)= 1/729
Each of two parents has the genotype brown/blue, which consists of the pair of alleles that determine eye color, and each parent contributes one of those alleles to a child. Assume that if the child has at least one brown allele, that color will dominate and the child's eye color will be brown. a. List the different possible outcomes. Assume that these outcomes are equally likely. b. What is the probability that a child of these parents will have the blue/blue genotype? c. What is the probability that the child will have brown eye color?
a. List the possible outcomes. brown/brown, brown/blue, blue/brown, and blue/blue b. The probability that a child of these parents will have the blue/blue genotype is 0.25 c. The probability that the child will have brown eye color is 0.75
At last night's basketball game, 2664 fans bought general admission tickets, 924 bought non-midcourt floor tickets, and 198 bought midcourt floor tickets. General admission tickets to the game cost $9.00, midcourt floor tickets cost $46.00, and non-midcourt floor tickets cost $24.00. Find the mean ticket price for last night's fans. Show your calculation as well as the answer rounded to two decimal places. Include the correct units in your answer.
see picture
A polling company reported that 27% of 1018 surveyed adults said that cellular phones are "quite annoying." Complete parts (a) through (d) below.
a. What is the exact value that is 27% of 1018? 27% of 1018 = 27/100 x 1018 = 274.86 b. Could the result from part (a) be the actual number of adults who said that cellular phones are "quite annoying"? Why or why not? No, the result from part (a) could not be the actual number of adults who said that cellular phones are "quite annoying" because a count of people must result in a whole number. c. What could be the actual number of adults who said that cellular phones are "quite annoying?" The polling company's report of 27% is an approximation rounded to the nearest whole number. Therefore, 274.86 approximates the actual number of adults who said that pollution is "very harmful." The closest whole number to 274.86 is 275 D. Among the 1018 respondents, 176 said that cellular phones are "not at all annoying." What percentage of respondents said that cellular phones are "not at all annoying"? 176/1018= 0.1729 x 100 = 17.29%
A polling company reported that 43% of 1013 surveyed adults said that pesticides are "very harmful." Complete parts (a) through (d) below.
a. What is the exact value that is 43% of 1013? 435.59 b. Could the result from part (a) be the actual number of adults who said that pesticides are "very harmful"? Why or why not? No, the result from part (a) could not be the actual number of adults who said that pesticides are "very harmful" because a count of people must result in a whole number. C. What could be the actual number of adults who said that pesticides are "very harmful"? 436 d. Among the 1013 respondents, 367 said that pesticides are "not at all harmful." What percentage of respondents said that pesticides are "not at all harmful" 36.23%
Identify which type of sampling is used: random, systematic, convenience, stratified, or cluster. To determine customer opinion of their pricing, Home Depot randomly selects 120 check out lines during a certain week and surveys all customers in the check out lines.
cluster
A _______ probability of an event is a probability obtained with knowledge that some other event has already occurred.
conditional
Identify which type of sampling is used: random, systematic, convenience, stratified, or cluster. A newspaper asks its readers to call in their opinion regarding the number of books they have read this month.
convenience
Events that are _______ cannot occur at the same time.
disjoint
Find the (a) mean, (b) median, (c) mode, and (d) midrange for the data and then (e) answer the given question. Listed below are foot lengths in inches of randomly selected women in a study of a country's military in 1988. Are the statistics representative of the current population of all women in that country's military? 9.8 10.5 9.3 10.5 8.6 8.7 8.9 9.5 9.2 9.3 9.3
e. Are the statistics representative of the current population of all women in that country's military? Choose the best answer below. Since the measurements were made in 1988, they are not necessarily representative of the current population of all women in the country's military.
Which of the following would be classified as categorical data?
hair color
A student's course grade is based on one midterm that counts as 5% of his final grade, one class project that counts as 5% of his final grade, a set of homework assignments that counts as 30% of his final grade, and a final exam that counts as 60% of his final grade. His midterm score is 60, his project score is 82, his homework score is 89, and his final exam score is 71. What is his overall final score? What letter grade did he earn (A, B, C, D, or F)? Assume that a mean of 90 or above is an A, a mean of at least 80 but less than 90 is a B, and so on.
how to do: A weighted mean equation. class project weight = 82 homework assignments = 89 midterm = 60 final exam = 71 enter into equation: (5x60) + (5x82) + (30 x 89) + (60 x 71) / 5 + 5 + 30 + 60 = His overall final score is 76.4. His letter grade is C.
Find the (a) mean, (b) median, (c) mode, and (d) midrange for the data and then (e) answer the given question. Listed below are the jersey numbers of 11 players randomly selected from the roster of a championship sports team. What do the results tell us? 53 76 20 47 2 6 28 89 66 83 94
stat crunch = stat, summary stats a. Find the mean. mean = Ex / n Ex = sum of all values n= number of data values sum/n B. mode - greatest frquency d. midrange midrange = minimum data value + maximum data value / 2 c. median e. what do the results tell us? The jersey numbers are nominal data and they do not measure or count anything, so the resulting statistics are meaningless.
A certain group of test subjects had pulse rates with a mean of 81.9 beats per minute and a standard deviation of 12.4 beats per minute. Use the range rule of thumb for identifying significant values to identify the limits separating values that are significantly low or significantly high. Is a pulse rate of 116.7 beats per minute significantly low or significantly high?
if the population mean is μ and the population standard deviation is σ, then the range rule of thumb for identifying significant values is as follows. Significantly low values are μ−2σ or lower. Significantly high values are μ+2σ or higher. Insignificant values are between (μ−2σ) and (μ+2σ). As given in the problem statement, the mean is μ=81.9 beats per minute and the standard deviation is σ=12.4 beats per minute. First, find μ−2σ. μ−2σ=(81.9)−2×(12.4)= 57.1 beats per minute Now find μ+2σ. μ+2σ=(81.9)+2×(12.4) =106.7 beats per minute significantly low values are 57.1 beats per minute or lower significantly high values are 106.7 beats per minute or higher. Is a pulse rate of 116.7 beats per minute significantly low or significantly high? significantly high because it is more than two standard deviations above the mean.
Two events A and B are _______ if the occurrence of one does not affect the probability of the occurrence of the other.
independent
When driving to Grandma's house, I drive on the highway for 2hours at 75mph, then through a large city for 1hour at 20mph, then on a county road for 6hours at 40mph. What is my mean speed for the entire trip? Round your answer to one decimal place.
mean speed: 45.6mph
Identify the level of measurement of the data, and explain what is wrong with the given calculation. In a survey, the political parties of respondents are identified as 100 for a Democrat, 200 for a Republican, 300 for a Libertarian, and 400 for anything else. The average (mean) is calculated for 757 respondents and the result is
nominal Such data are not counts or measures of anything, so it makes no sense to compute their average (mean).
The complement of "at least one" is _______.
none
Among fatal plane crashes that occurred during the past 70 years, 504 were due to pilot error, 89 were due to other human error, 501 were due to weather, 102 were due to mechanical problems, and 584 were due to sabotage.
percentage for a class= frequency for a class / sum of all frequencies x 100% create table: pilot error = 28.3% other human error = 5% weather = 28.1 % mechanical problems = 5.7% sabotage = 32.8% sabotage is the most serious threat to aviation safety. Airport security could be increased.
Identify the type of sampling used (random, systematic, convenience, stratified, or cluster sampling) in the situation described below. In a poll conducted by a certain research center, 969 adults were called after their telephone numbers were randomly generated by a computer, and 91% were able to correctly identify the president
random sampling
A city council collected data on driving speeds in order to decide on appropriate speed limits. On a major street the mean speed was 39.4 mph, with a standard deviation of 5.4 mph. On a residential street, speeds had a mean of 22.4 mph and a standard deviation of 2.6 mph. Relative to the other traffic on that street, which of the following speeds is greater: 48 mph on the major street or 27 mph on the residential street? Show the calculations that justify your answer; round the results to two decimal places.
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A jar contains 17 balls, labeled 1-17. A ball is randomly selected to determine a lottery winner. What is the probability that the selected ball has an even number or a number less than 8? Justify your answer using the Addition Rule. Write your answer as either a reduced fraction or a decimal rounded to three decimal places.
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A junkyard has 20 tires for sale. Of the 20, 3 have some undetected damage, and the other 17 are undamaged. A customer randomly selects five different tires to buy. What is the probability that all five tires are undamaged? Show your calculation, and write your answer as either a reduced fraction or a decimal rounded to three places.
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A landscaper wants to plant 6 oak trees, 5 maple trees, and 5 poplar trees along one side of a lawn. The trees are to be evenly spaced, and trees of the same kind are indistinguishable. In how many distinguishable ways can they be planted? Show your calculation and the answer.
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Heights of male students at a particular university are normally distributed, with a mean of 68.4 inches and a standard deviation of 3.4 inches. Give a height that is either significantly low or significantly high, and another height that is not significant (be sure to clearly indicate which is which!). Explain your answers.
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In a tropical location, there is a 86% chance of rain each day. What is the probability that a 5-day period will have at least one day without rain? Show your calculation, and round your answer to four decimal places.
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