BUSA 3131 Final Study Guide
Testbank Question 4.33 Let F be the event that a student is enrolled in a finance course, and let S be the event that a student is enrolled in a statistics course. It is known that 40% of all students are enrolled in a finance course and 35% of all students are enrolled in statistics. Included in these numbers are 15% who are enrolled in both statistics and finance. A student is randomly selected, what is the probability that the student is enrolled in either finance or statistics or both?
.60
Testbank Question 6.36 Correct answer. Your answer is correct. If x, the time (in minutes) to complete an change job at certain auto service station, is uniformly distributed over the interval 20 to 30, inclusively (20 ≤ x ≤ 30), then the probability that an oil change job is completed in less than 17 minutes, i.e., P( x < 17) is __________________.
0.0000
Testbank Question 4.61 It is known that 20% of all students in some large university are overweight, 20% exercise regularly and 2% are overweight and exercise regularly. What is the probability that a randomly selected student is overweight given that this student exercises regularly?
.10
Testbank Question 8.60 Correct answer. Your answer is correct. Catherine Chao, Director of Marketing Research, is evaluating consumer acceptance of a new toothpaste package. She randomly selects a sample of 200 households. Forty households prefer the new package to all other package designs. The point estimate for this population proportion is _______.
.20
Testbank Question 6.33 Correct answer. Your answer is correct. If x, the time (in minutes) to complete an change job at certain auto service station, is uniformly distributed over the interval 20 to 30, inclusively (20 ≤ x ≤ 30), then the probability that an oil change job is completed in 25 to 28 minutes, inclusively, i.e., P(25 ≤ x ≤ 28) is __________________.
.3
Testbank Question 8.74 Correct answer. Your answer is correct. In estimating the sample size necessary to estimate p, if there is no good approximation for the value of p available, the value of ____ should be used as an estimate of p in the formula.
.50
Practice Question 7.48 Correct answer. Correct! Public-opinion polls are conducted by a survey company to estimate the fraction of U.S. citizens who trust the president. Suppose 2000 people are randomly chosen and 1587 answer that they trust the president. What is the point estimate of the population proportion (p = 0.81) who trust the president? What are the mean and standard deviation of p ?
0.7935, 0.81 and 0.0088
Testbank Question 5.41 Correct answer. Your answer is correct. If x is a binomial random variable with n = 10 and p = 0.8, the standard deviation of x is _________.
1.26
Testbank Question 5.56 Correct answer. Your answer is correct. A large industrial firm allows a discount on any invoice that is paid within 30 days. Of all invoices, 10% receive the discount. In a company audit, 15 invoices are sampled at random. The mean (average) value of the number of the 15 sampled invoices that receive discount is _______.
1.5
Practice Question 6.17 Correct answer. Correct! The values of a random variable are uniformly distributed between 20 and 70. The standard deviation of this distribution is __________.
14.43
Practice Question 4.20 How many elementary events are in the sample space of the experiment of rolling a 6-faced die thrice?
216
Practice Question 5.25 Correct answer. Correct! What is the variance of a binomial distribution in which the number of trials n = 100 and the probability of success p = 0.5?
25
Practice Question 6.16 Correct answer. Correct! The values of a random variable are uniformly distributed between 20 and 70. The mean of this distribution is __________.
45
Practice Question 7.41 Correct answer. Correct! The average salary of a travel management professional is $98,500. Assume that the standard deviation of such salaries is $40,000. A random sample of 100 travel management professionals are selected, then the mean and standard deviation of the sampling mean is __________.
98500 and 4000
Practice Question 7.33 Correct answer. Correct! If reasonably large sized samples (i.e., samples of 30 elements or more) are drawn from a binomial distribution, the sample means will be approximately __________.
normally distributed
Practice Question 7.34 Correct answer. Correct! If reasonably large sized samples (i.e., samples of 30 elements or more) are drawn from a Poisson distribution, the sample means will be approximately __________.
normally distributed
Practice Question 9.24 Correct answer. Correct! A Type II error is committed when the null hypothesis is false and it is not rejected. A Type II error is committed when __________.
the null hypothesis is false and it is not rejected
Practice Question 9.23 Correct answer. Correct! A Type I error is committed when the null hypothesis is true and it is rejected. A Type I error is committed when __________.
the null hypothesis is true and it is rejected
Testbank Question 4.23 Consider the following sample space, S, and several events defined on it. S = {Albert, Betty, Abel, Jack, Patty, Meagan}, and the events are: F = {Betty, Patty, Meagan}, H = {Abel, Meagan}, and P = {Betty, Abel}. F∩H is ___________.
{Meagan}
Supplementary Problem 3.39 Correct answer. Correct. The 2010 U.S. Census asked every household to report information on each person living there. Suppose for a sample of 30 households selected, the number of persons living in each was reported as follows. 3 3 1 2 6 4 2 1 5 3 2 3 1 2 2 1 3 1 2 2 4 2 1 2 10 3 2 1 1 3 Compute the mean, median, mode, range, lower and upper quartiles, and interquartile range for these data.
Mean = Entry field with correct answer 2.6 , mode = Entry field with correct answer 2 , median = Entry field with correct answer 2 , range = Entry field with correct answer 9 , = Entry field with correct answer 1 , = Entry field with correct answer 3 , IQR = Entry field with correct answer 2
End of Section Problem 5.1 Correct answer. Correct. Determine the mean, the variance, and the standard deviation of the following discrete distribution. x P(x) 1 0.210 2 0.326 3 0.183 4 0.144 5 0.137
Mean, μ = Entry field with correct answer 2.672 Variance, σ2 = Entry field with correct answer 1.752 Standard deviation, σ = Entry field with correct answer 1.324
Practice Question 4.17 If two events, Event A with probability P(A) and Event B with probability P(B) are mutually exclusive, then __________.
P (A ∩ B) = 0
End of Section Problem 6.9 Correct answer. Correct. According to the Internal Revenue Service, income tax returns one year averaged $1,332 in refunds for taxpayers. One explanation of this figure is that taxpayers would rather have the government keep back too much money during the year than to owe it money at the end of the year. Suppose the average amount of tax at the end of a year is a refund of $1,332, with a standard deviation of $725. Assume that amounts owed or due on tax returns are normally distributed. (a) What proportion of tax returns show a refund greater than $2,200? (b) What proportion of the tax returns show that the taxpayer owes money to the government? (c) What proportion of the tax returns show a refund between $120 and $690?
(Round all the z values to 2 decimal places. Round your answers to 4 decimal places.) (a) P(x > $2,200) = Entry field with correct answer 0.1151 (b) P(x < 0) = Entry field with correct answer 0.0329 (c) P($120 ≤ x ≤ $690) = Entry field with correct answer 0.1392
End of Section Problem 8.34 Correct answer. Your answer is correct. Suppose a survey of 275 executives is taken in an effort to determine what qualities are most important for an effective CEO to possess. The survey participants are offered several qualities as options, one of which is "communication." One hundred twenty-one of the surveyed respondents select "communicator" as the most important quality for an effective CEO. Use these data to construct a 98% confidence interval to estimate the population proportion of executives who believe that "communicator" is the most important quality of an effective CEO.
(Round the answers to 2 decimal places.) Entry field with correct answer .37 ≤ p ≤ Entry field with correct answer .51
End of Section Problem 5.4 Correct answer. Your answer is correct. Suppose 20% of the people in a city prefer Pepsi-Cola as their soft drink of choice. If a random sample of six people is chosen, the number of Pepsi drinkers could range from zero to six. Shown here are the possible numbers of Pepsi drinkers in a sample of six people and the probability of that number of Pepsi drinkers occurring in the sample. Use the data to determine the mean number of Pepsi drinkers in a sample of six people in the city, and compute the standard deviation. Number of Pepsi Drinkers Probability 0 0.262 1 0.393 2 0.246 3 0.082 4 0.015 5 0.002 6 0.000
(Round the intermediate values and final answers to 3 decimal places.) = Entry field with correct answer 1.201 = Entry field with correct answer 0.963 = Entry field with correct answer 0.981
End of Section Problem 8.21 Correct answer. Correct. The marketing director of a large department store wants to estimate the average number of customers who enter the store every five minutes. She randomly selects five-minute intervals and counts the number of arrivals at the store. She obtains the figures 52, 32, 41, 48, 56, 80, 43, 29, 32, and 74. The analyst assumes the number of arrivals is normally distributed. Using these data, the analyst computes a 95% confidence interval to estimate the mean value for all five-minute intervals. What interval values does she get?
(Round the intermediate values to 2 decimal places. Round your answers to 2 decimal places.) Entry field with correct answer 36.26 ≤ μ ≤ Entry field with correct answer 61.14
Supplementary Problem 8.63 Correct answer. Correct. A national survey of insurance offices was taken, resulting in a random sample of 237 companies. Of these 237 companies, 174 responded that they were going to purchase new software for their offices in the next year. Construct a 90% confidence interval to estimate the population proportion of insurance offices that intend to purchase new software during the next year.
(Round the intermediate values to 2 decimal places. Round your answers to 3 decimal places.) Entry field with correct answer 0.683 ≤ p ≤ Entry field with correct answer .777
End of Section Problem 8.17 Correct answer. Correct. Use the following data to construct a 99% confidence interval for μ. 17.6 17.1 17.0 15.6 16.2 15.0 16.0 15.6 17.3 17.4 15.6 15.7 17.2 16.6 16.0 15.3 15.4 16.5 15.8 17.2 14.6 15.5 14.9 16.7 16.4 Assume x is normally distributed. What is the point estimate for μ?
(Round the intermediate values to 3 decimal places. Round your answers to 3 decimal places.) Entry field with correct answer 15.686 ≤ μ ≤ Entry field with correct answer 16.650 The point estimate for μ is Entry field with correct answer 16.168 .
Supplementary Problem 6.57 Correct answer. Correct. According to the Air Transport Association of America, the average operating cost of an MD-80 jet airliner is $2,087 per hour. Suppose the operating costs of an MD-80 jet airliner are normally distributed with a standard deviation of $175 per hour.
(Round the value of z to 2 decimal places. Round your answers to 2 decimal places.) (a) At what operating cost would only 20% of the operating costs be less? $Entry field with correct answer 1,940.00 (b) At what operating cost would 65% of the operating costs be more? $Entry field with correct answer 2,018.75 (c) What operating cost would be more than 85% of operating costs? $Entry field with correct answer 2,269.00
End of Section Problem 6.7 Correct answer. Correct. Tompkins Associates reports that the mean clear height for a Class A warehouse in the United States is 22 feet. Suppose clear heights are normally distributed and that the standard deviation is 4 feet. A Class A warehouse in the United States is randomly selected. (a) What is the probability that the clear height is greater than 14 feet? (b) What is the probability that the clear height is less than 12 feet? (c) What is the probability that the clear height is between 25 and 30 feet?
(Round the values of z to 2 decimal places. Round your answers to 4 decimal places.) (a) P(x > 14) = Entry field with correct answer 0.9772 (b) P(x < 12) = Entry field with correct answer 0.0062 (c) P(25 ≤ x ≤ 30) = Entry field with correct answer 0.2038
End of Section Problem 6.11 Correct answer. Correct. Suppose you are working with a data set that is normally distributed, with a mean of 350 and a standard deviation of 46. Determine the value of x from the following information.
(Round your answers and z values to 2 decimal places.) (a) 70% of the values are greater than x. Entry field with correct answer 326.08 (b) x is less than 16% of the values. Entry field with correct answer 395.54 (c) 23% of the values are less than x. Entry field with correct answer 315.96 (d) x is greater than 57% of the values. Entry field with correct answer 358.28
6a Correct Distribution Correct answer. According to a survey conducted by a market research company, 60% of all consumers have called an 800 or 900 telephone number for information about some product. Suppose a random sample of 20 consumers is contacted and interviewed about their buying habits. The number of customers who have called for information follows which distribution below?
Binomial
End of Section Problem 2.3 Correct answer. Correct. The owner of a fast-food restaurant ascertains the ages of a sample of customers. From these data, the owner constructs the frequency distribution shown. For each class interval of the frequency distribution, determine the class midpoint, the relative frequency, and the cumulative frequency. Class Interval Frequency 0 - under 5 6 5 - under 10 6 10 - under 15 18 15 - under 20 24 20 - under 25 18 25 - under 30 9 30 - under 35 4 What does the relative frequency tell the fast-food restaurant owner about customer ages?
Class Interval Frequency Class Midpoint Relative Frequency Cummulative Frequency 0 - under 5 6 Entry field with correct answer 2.5 Entry field with correct answer 0.0706 Entry field with correct answer 6 5 - under 10 6 Entry field with correct answer 7.5 Entry field with correct answer 0.0706 Entry field with correct answer 12 10 - under 15 18 Entry field with correct answer 12.5 Entry field with correct answer .2118 Entry field with correct answer 30 15 - under 20 24 Entry field with correct answer 17.5 Entry field with correct answer .2824 Entry field with correct answer 54 20 - under 25 18 Entry field with correct answer 22.5 Entry field with correct answer .2118 Entry field with correct answer 72 25 - under 30 9 Entry field with correct answer 27.5 Entry field with correct answer .1059 Entry field with correct answer 81 30 - under 35 4 Entry field with correct answer 32.5 Entry field with correct answer .0471 Entry field with correct answer 85 TOTAL Entry field with correct answer 85 The relative frequency tells us that it is most probable that a customer is in the 15-20category. Over two thirds of the customers are between 10 and 25 age.
Supplementary Problem 2.26 Correct answer. Correct. For each class interval of the frequency distribution given, determine the class midpoint, the relative frequency, and the cumulative frequency. (Round relative frequency to 3 decimal places.) Class Interval Frequency 20-under 25 17 25-under 30 20 30-under 35 16 35-under 40 15 40-under 45 8 45-under 50 6
Class Interval Frequency Class Midpoint Relative Frequency Cumulative Frequency 20-under 25 17 Entry field with correct answer 22.5 Entry field with correct answer .207 Entry field with correct answer 17 25-under 30 20 Entry field with correct answer 27.5 Entry field with correct answer .244 Entry field with correct answer 37 30-under 35 16 Entry field with correct answer 32.5 Entry field with correct answer .195 Entry field with correct answer 53 35-under 40 15 Entry field with correct answer 37.5 Entry field with correct answer .183 Entry field with correct answer 68 40-under 45 8 Entry field with correct answer 42.5 Entry field with correct answer .098 Entry field with correct answer 76 45-under 50 6 Entry field with correct answer 47.5 Entry field with correct answer .073 Entry field with correct answer 82
End of Section Problem 3.12 Correct answer. Correct. A data set contains the following eight values. 4 3 0 5 2 9 4 5
Find the range. Entry field with correct answer 9 b. Find the mean absolute deviation. Entry field with correct answer 1.75 (Round your answer to 2 decimal places.) c. Find the sample variance. Entry field with correct answer 6.857 (Round your answer to 4 decimal places.) d. Find the sample standard deviation. Entry field with correct answer 2.6186 (Round your answer to 4 decimal places.) e. Find the interquartile range. Entry field with correct answer 2.5 (Round your answer to 1 decimal place.)
Practice Question 4.11 If the occurrence or non occurrence of one event does not affect the occurrence or non occurrence of another event, the two events are ________________________.
Independent
Testbank Question 4.62 A market research firm is investigating the appeal of three package designs. The table below gives information obtained through a sample of 200 consumers. The three package designs are labeled A, B, and C. The consumers are classified according to age and package design preference. A B C Total Under 25 years 22 34 40 96 25 or older 54 28 22 104 Total 76 62 62 200 Are "B" and "25 or older" independent and why or why not?
No, because P (25 or older | B)P (25 or older)
Practice Question 1.30 What is the level of data corresponding to a military rank (Lieutenant, Captain, Major)?
Ordinal
Testbank Question 1.67 Sue Taylor, Director of Global Industrial Sales, is concerned by a deteriorating sales trend. Specifically, the number of customers is stable at 1,500, but they are purchasing less each year. She orders her staff to search for causes of the downward trend by surveying all 1,500 industrial customers. One question on the survey asked the customers: "How many people does your company employ? The measurement level for this question is __________.
Ratio Level
End of Section Problem 3.14 Correct answer. Correct. Use your calculator or computer to find the sample variance and sample standard deviation for the following data. 57 88 68 43 93 63 51 37 77 83 66 60 38 52 28 34 52 60 57 29 92 37 38 17 67
Sample variance = Entry field with correct answer 433.9267 , sample standard deviation = Entry field with correct answer 20.8309
Testbank Question 2.34 Abel Alonzo, Director of Human Resources, is exploring employee absenteeism at the Harrison Haulers Plant during the last operating year. A review of all personnel records indicated that absences ranged from zero to twenty-nine days per employee. The following class intervals were proposed for a frequency distribution of absences. Absences (Days) Number of Graduates 0-under 5 - 5-under 10 - 10-under 15 - 20-under 25 - 25-under 30
Some numbers between 0 and 29, inclusively, would not fall into any interval.
Testbank Question 1.30 Sue Taylor, Director of Global Industrial Sales, is concerned by a deteriorating sales trend. Specifically, the number of industrial customers is stable at 1,500, but they are purchasing less each year. She orders her staff to search for causes of the downward trend by surveying all 1,500 industrial customers. For this study, the set of 1,500 industrial customers is ______________.
The Population
Testbank Question 1.32 Miguel Hernandez , Senior Vice President of Human Resources at Memorial Hospital, is exploring the usage of nursing over-time hours in the emergency department during the last operating year (January 1, 2012 through December 31, 2012). Miguel intends to survey the emergency department nurses regarding their perception of over-time needs. For this survey y the set of all emergency department nurses who worked at Memorial Hospital during the last operating year is _________.
The Population
Two Measures of Center The histogram of US household income is highly skewed to the right, with a small number of extremely high incomes that are possibly outliers. Given this, which of the following statistics best describes the center of the distribution?
The median
CI Interpretation Correct answer. What proportion of pizza restaurants that are primarily for walk-in business have a salad bar? Suppose that, in an effort to determine this figure, a random sample of 1,250 of these restaurants across the United States based on the Yellow Pages is called, and 900 of the restaurants sampled have a salad bar. Based on this, a 99% confidence interval of the proportion of pizza restaurants with a salad bar is found to be 68.73% and 75.27%. This interval means:
The method used to calculate the confidence interval is correct 99% of the time (i.e., the interval will include the population proportion).
Interpretation of Conclusion Correct answer. The speed limit on a highway is 65 miles per hour. Highway patrol is evaluating potential locations for a new radar trap. If the average driving speed on a segment of this highway is higher than 65 mph, then a radar trap will be setup in this location. 50 driving speeds were randomly sampled near one of the potential locations and used to test the following hypotheses: Ho: the average driving speed at this location is not higher than 65 mph. Ha: the average driving speed at this location is higher than 65 mph. Based on the sample evidence, the null hypothesis is rejected at 5% significance level. This conclusion means:
The sample evidence indicates the average driving speed is higher than 65 mph, but there is a maximum of 5% chance that this conclusion is wrong.
Testbank Question 2.33 The following class intervals for a frequency distribution were developed to provide information regarding the starting salaries for students graduating from a particular school: Salary Number of Graduates ($1,000s) 28-under 31 - 31-under 35 - 34-under 37 - 39-under 40 - Before data was collected, someone questioned the validity of this arrangement. Which of the following represents a problem with this set of intervals?
The second and the third interval overlap.
Supplementary Problem 9.57 Correct answer. Correct. Suppose the number of beds filled per day in a mediumsized hospital is normally distributed. A hospital administrator tells the board of directors that, on the average, at least 184 beds are filled on any given day. One of the board members believes that the average is less than 184 and she sets out to test to determine if she is correct. She secures a random sample of 16 days of data (shown below). Use α = 0.1 and the sample data to test the board member's theory. Assume the number of filled beds per day is normally distributed in the population. Number of Beds Occupied per Day 173 149 166 180 189 169 152 194 177 169 188 160 199 175 172 187
The value of the test statistic is Entry field with correct answer -2.53 and we reject the null hypothesis
End of Section Problem 9.19 Correct answer. Correct. Suppose that in past years the average price per square foot for warehouses in the United States has been $32.24. A national real estate investor wants to determine whether that figure has changed now. The investor hires a researcher who randomly samples 49 warehouses that are for sale across the United States and finds that the mean price per square foot is $31.68, with a standard deviation of $1.25. Assume that prices of warehouse footage are normally distributed in population. If the researcher uses a 5% level of significance, what statistical conclusion can be reached? (Round your answer to 2 decimal places.)
The value of the test statistic is Entry field with correct answer -3.14 and we reject the null hypothesis.
End of Section Problem 9.31 Correct answer. Correct. A large manufacturing company investigated the service it received from suppliers and discovered that, in the past, 31% of all materials shipments were received late. However, the company recently installed a just-in-time system in which suppliers are linked more closely to the manufacturing process. A random sample of 126 deliveries since the just-in-time system was installed reveals that 21 deliveries were late. Use this sample information to test whether the proportion of late deliveries was reduced significantly. Let α = 0.05.
The value of the test statistic is Entry field with correct answer -3.47 and we reject the null hypothesis
End of Section Problem 9.28 Correct answer. Correct. A study by Hewitt Associates showed that 79% of companies offer employees flexible scheduling. Suppose a researcher believes that in accounting firms this figure is lower. The researcher randomly selects 415 accounting firms and through interviews determines that 303 of these firms have flexible scheduling. With a 1% level of significance, does the test show enough evidence to conclude that a significantly lower proportion of accounting firms offer employees flexible scheduling?
The value of the test statistic is z = Entry field with correct answer -3 and we reject the null hypothesis
Practice Question 2.26 Cumulative frequency for an individual class is the __________.
individual class frequency plus the total frequency of all preceding classes
Practice Question 5.14 Correct answer. Correct! The average time of students spend on reading per day is __________.
a continuous random variable
Testbank Question 5.24 Correct answer. Your answer is correct. The volume of liquid in an unopened 1-gallon can of paint is an example of _________.
a continuous random variable
10b Type of Test Correct answer. A manufacturing company claims the average weight of their large box of popcorn is at least 32 ounces. Which one of the following procedures is the most appropriate to test this claim?
a one-tailed test for population mean
10a Types of Test Correct answer. We wish to test if more than 40% of adult women in US actively participate in the workforce. The most appropriate statistical inference tool to use is
a one-tailed test for population proportion
Supplementary Problem 7.43 Correct answer. Correct. The Aluminum Association reports that the average American uses 56.8 pounds of aluminum in a year. A random sample of 51 households is monitored for one year to determine aluminum usage. If the population standard deviation of annual usage is 12.1 pounds, what is the probability that the sample mean will be each of the following?
a. More than 61 pounds b. More than 56 pounds c. Between 55 and 58 pounds d. Less than 53 pounds e. Less than 48 pounds (Round the values of z to 2 decimal places. Round your answers to 4 decimal places.) a. Entry field with correct answer 0.0066 b. Entry field with correct answer 0.6808 c. Entry field with correct answer 0.6165 d. Entry field with correct answer 0.0125 e. Entry field with correct answer 0.0000
Supplementary Problem 4.35 Correct answer. Corrrect. Use the values in the cross-tabulation table to solve the equations given. Variable 1 Variable 2 D E A 11 21 B 15 6 C 29 16
a. P(E) = Entry field with correct answer 0.43878 * b. P(BD) = Entry field with correct answer 0.62245 * c. P(AE) = Entry field with correct answer 0.21429 * d. P(B | E) = Entry field with correct answer 0.13953 * e. P(AB) = Entry field with correct answer 0.54082 * f. P(BC) = Entry field with correct answer .0000 ** g. P(D | C) = Entry field with correct answer 0.64444 * h. P(A | B) = Entry field with correct answer .0000 ** i. Are variables 1 and 2 independent? Variables 1 and 2 are not independent
Supplementary Problem 4.36 Correct answer. Corrrect. Use the values in the cross-tabulation table to solve the equations given. D E F G A 3 9 7 12 B 8 4 6 4 C 10 5 3 7
a. P(FA) = Entry field with correct answer .08974 (Round your answer to 5 decimal places.) b. P(A|B) = Entry field with correct answer .0000 (Round your answer to 4 decimal places.) c. P(B) = Entry field with correct answer .28205 (Round your answer to 5 decimal places.) d. P(EF) = Entry field with correct answer .0000 (Round your answer to 4 decimal places.) e. P(D|B) = Entry field with correct answer .36364 (Round your answer to 5 decimal places.) f. P(B|D) = Entry field with correct answer .38095 (Round your answer to 5 decimal places.) g. P(DC) = Entry field with correct answer .4615 (Round your answer to 4 decimal places.) h. P(F) = Entry field with correct answer .20513 (Round your answer to 5 decimal places.)
End of Section Problem 5.13 Correct answer. Correct. An increasing number of consumers believe they have to look out for themselves in the marketplace. According to a survey conducted by the Yankelovich Partners for USA WEEKEND magazine, 60% of all consumers have called an 800 or 900 telephone number for information about some product. Suppose a random sample of 19 consumers is contacted and interviewed about their buying habits.
a. What is the probability that 11 or more of these consumers have called an 800 or 900 telephone number for information about some product? Entry field with correct answer 0.668 b. What is the probability that more than 14 of these consumers have called an 800 or 900 telephone number for information about some product? Entry field with correct answer 0.070 c. What is the probability that fewer than 7 of these consumers have called an 800 or 900 telephone number for information about some product? Entry field with correct answer 0.011
End of Section Problem 5.11 Correct answer. Correct. What is the first big change that American drivers made due to higher gas prices? According to an Access America survey, 20% said that it was cutting recreational driving. However, 25% said that it was consolidating or reducing errands. If these figures are true for all American drivers, and if 20 such drivers are randomly sampled and asked what is the first big change they made due to higher gas prices?
a. What is the probability that exactly 8 said that it was consolidating or reducing errands? Entry field with correct answer 0.0609 * b. What is the probability that none of them said that it was cutting recreational driving? Entry field with correct answer 0.0115292 ** c. What is the probability that more than 7 said that it was cutting recreational driving? Entry field with correct answer 0.031 ***
Supplementary Problem 4.37 Correct answer. Corrrect. The following joint probability table contains a breakdown on the age and gender of U.S. physicians in a recent year, as reported by the American Medical Association. U.S. PHYSICIANS IN A RECENT YEAR Age (Years) Gender Male Female < 35 35 - 44 45 - 54 55 - 64 > 65 0.11 0.20 0.19 0.13 0.15 0.78 0.07 0.05 0.07 0.02 0.01 0.22 0.18 0.25 0.26 0.15 0.16 1.00
a. What is the probability that one randomly selected physician is 35-44 years old? (Round your answer to 2 decimal places.) Entry field with correct answer 0.25 b. What is the probability that one randomly selected physician is both a woman and 45-54 years old? (Round your answer to 2 decimal places.) Entry field with correct answer 0.07 c. What is the probability that one randomly selected physician is a man or is 35-44 years old? (Round your answer to 2 decimal places.) Entry field with correct answer 0.83 d. What is the probability that one randomly selected physician is less than 35 years old or 55-64 years old? (Round your answer to 2 decimal places.) Entry field with correct answer 0.33 e. What is the probability that one randomly selected physician is a woman if she is 45-54 years old? (Round your answer to 4 decimal places.) Entry field with correct answer 0.2692 f. What is the probability that a randomly selected physician is neither a woman nor 55-64 years old? (Round your answer to 2 decimal places.) Entry field with correct answer 0.65
End of Section Problem 7.18 Correct answer. Your answer is correct. The Statistical Abstract of the United States published by the U.S. Census Bureau reports that the average annual consumption of fresh fruit per person is 99.9 pounds. The standard deviation of fresh fruit consumption is about 30 pounds. Suppose a researcher took a random sample of 38 people and had them keep a record of the fresh fruit they ate for one year.
a. What is the probability that the sample average would be less than 90 pounds? p = Entry field with correct answer 0.0212 b. What is the probability that the sample average would be between 98 and 105 pounds? p = Entry field with correct answer 0.5048 c. What is the probability that the sample average would be less than 112 pounds? p = Entry field with correct answer 0.9936 d. What is the probability that the sample average would be between 93 and 96 pounds? p = Entry field with correct answer 0.1341
Practice Question 4.36 The probability of one event given the information that another related event has occurred is an example of __________.
conditional probability
Testbank Question 9.33 Correct answer. Your answer is correct. Consider the following null and alternative hypotheses. Ho: μ ≥ 67 Ha: μ < 67 These hypotheses _______________.
indicate a one-tailed test with a rejection area in the left tail
Testbank Question 9.32 Correct answer. Your answer is correct. Consider the following null and alternative hypotheses. Ho: μ ≤67 Ha: μ > 67 These hypotheses _______________.
indicate a one-tailed test with a rejection area in the right tail
Practice Question 2.25 Relative frequency for an individual class is the __________.
individual class frequency divided by the total frequency
Testbank Question 9.61 Correct answer. Your answer is correct. The weight of a USB flash drive is 30 grams and is normally distributed. Periodically, quality control inspectors at Dallas Flash Drives randomly select a sample of 17 USB flash drives. If the mean weight of the USB flash drives is too heavy or too light the machinery is shut down for adjustment; otherwise, the production process continues. The last sample showed a mean and standard deviation of 31.9 and 1.8 grams, respectively. The null hypothesis is ______.
μ = 30
