stats final sum 2023 part 1
For a 90% confidence interval, α= ____ , and α / 2= ____.
0.10,0.05
An insurance company study shows that 60% of the auto insurance claims submitted for property damage were submitted by males under 25 years of age. Suppose 8 property damage claims involving automobiles are selected at random from that region. Let x be the number of claims (among the 8 selected) that were made by males under the age of 25. To find the probability that exactly 6 of the 8 claims are made by males under 25, we would use the binomial distribution with p= ____.
0.6
Samples of rejuvenated mitochondria are mutated (defective) in 1% of cases. Suppose that 150 samples are studied. If X is the number of mutated mitochondria in the sample, then X is binomial with n= ____, p = ____.
150, 0.01
17% of victims of financial fraud know the perpetrator of the fraud personally. Let X be the number of people in a random sample of 25 victims of financial fraud who knew the perpetrator personally. Then X is binomial with n = ____, p = _____
25, 0.17
In a random experiment a fair die is rolled seven times. If the random variable Y counts the number of times a 3 is rolled, then X is a binomial random variable with two parameters n = ____, p = ____
7, 1/6
An insurance company study shows that 60% of the auto insurance claims submitted for property damage were submitted by males under 25 years of age. Suppose 8 property damage claims involving automobiles are selected at random from that region. Let x be the number of claims (among the 8 selected) that were made by males under the age of 25. To find the probability that exactly 6 of the 8 claims are made by males under 25, we would use the binomial distribution with n=____
8
A zookeeper takes a sample of 50 penguins and finds their average weight to be 51 lb with a standard deviation of 4 lb. How would you find a z-score corresponding to a penguin that weighs 52 lb in Excel?
=(52-51)/4
How would you find the mean of data in the range A1 to A6 in Excel?
=AVERAGE(A1:A6)
To calculate z α / 2 in Excel, use the function _____ .
=NORM.INV(1-alpha/2, 0, 1)
Using Excel, how would you find the standard deviation for a sample of student's GPAs located in cells B1 to B10 ?
=ST.DEV.S(B1:B10)
A chef wants to make a dish that scales with the size of the potato used. If the potato is above 2.5 in in diameter or below 1.5 in diameter, he must change the other ingredients. He takes a sample of 40 random potatoes and finds their mean diameter is 1.75 in with a standard deviation of 0.1 in. What is the probability that a randomly selected potato is above 2.5" or below 1.5"?A. =NORM.DIST(1.5, 1.75, 0.1, TRUE) + (1- NORM.DIST(2.5, 1.75, 0.1, TRUE)) B. =NORM.DIST(2.5, 1.75, 0.1, TRUE) - NORM.DIST(1.5, 1.75, 0.1, TRUE) C. =NORM.DIST(1.5, 1.75, 0.1, TRUE) - NORM.DIST(2.5, 1.75, 0.1, TRUE) D. =NORM.DIST(1.5, 1.75, 0.1, TRUE) + NORM.DIST(2.5, 1.75, 0.1, TRUE)
A
A city government asks 500 randomly selected people whether or not they are employed. The population percentage of employment is 0.60. Which equation would calculate the probability that less than 300 of these people are employed? A. =BINOM.DIST(300, 500, 0.60, TRUE) B. =NORM.DIST(300, 0.60, 500/SQRT(300),TRUE) C. =T.DIST(300, 499, TRUE) D. =BINOM.DIST(300, 500, 0.60, FALSE)
A
A geographer randomly selects twenty points in a county to study the elevation. One point is on a large hill while the other points are near water level. What is the shape of the distribution? A. Skewed right B. Skewed left C. Symmetric
A
A psychologist wants to study whether there is a correlation between sleep deprivation and the diagnosis of ADD in students. She randomly selects 20 students who are diagnosed with ADD and times how long they are asleep. She found the students slept, on average, six hours a night. What is the population? a. Students diagnosed with ADD b. The students studied who didn't get enough sleep c. Everyone with sleep deprivation d. The 20 students studied e. The average of six hours f. Students g. Everyone with ADD
A
A psychologist wants to study whether there is a correlation between sleep deprivation and the diagnosis of ADD in students. She randomly selects 20 students who are diagnosed with ADD and times how long they are asleep. She found the students slept, on average, six hours a night. What is the sample? A. The 20 students studied B. Students diagnosed with ADD C. Everyone with ADD D. Everyone with sleep deprivation E. Students F. The students studied who didn't get enough sleep G. The average of six hours
A
A randomly selected sample of size 19 has a mean of 3 and a standard deviation of 1. Assume the population is normally distributed. A. =T.DIST(1.3, 18, TRUE) B. = T.DIST(1.3, 19, FALSE) C. =T.DIST(1.3, 3, 1/SQRT(19), TRUE) D. T.DIST(1.3- 1, 3, 1, TRUE) E. = 1 - T.DIST(1.3, 18, TRUE) F. =T.DIST(1.3 0, 1, TRUE) G. =T.DIST(1.3, 3, 1, TRUE) H. =T.DIST(1 - 1.3, 18, TRUE) I. =T.DIST(1.3, 19, TRUE) J. =1 - T.DIST(1.3, 19, TRUE) K. =T.DIST(1.3 - 1, 19, TRUE) L. =1 - T.DIST(1.3, 3, 1, TRUE) M =Z.DIST(1.3 3, 1, TRUE)-
A
A researcher wants to determine the average income of the employed people of Omaha, Nebraska. He found that there are 385,600 employed people in the state. A group of 1,200 people are selected randomly to ascertain the income of each of those individuals. He finds that the average income of those 1,200 numbers to be $42,827. Identify the population in this context. A. 385,600 employed people in Omaha B. 1,200 people selected for the study C. Average income of $42,827 D. 385,600 - 1,200 constitute the population E. 385,600 + 1,200 constitute the population
A
An observation that is radically different from the rest is called A. an outlier B. the median C. the mode D. the mean E. the variance F. a variant
A
Food scientists conduct a survey of randomly selected individuals to find out the percentage of people who think a hot dog is a sandwich.What distribution should they use to make a confidence interval for the population proportion? A. z distribution B. p distribution C. They should use either a z or t distribution depending on how big their sample size is. D. t distribution E. c distribution
A
Suppose we are working within a normal distribution. Which function finds an event's value given the probability of an event? A. =NORM.DIST() B. =NORM.INV() C. =PROBABILITY() D. =STAND.DIST()
A
The sampling distribution of sample means _____________. A. can be used to create a confidence interval for the population mean. B. becomes more skewed with each additional sample. C. always approximates a normal distribution. D. has the same mean and standard deviation as any one sample.
A
When is the mode most useful? A. Categorical data B. Numerical data C. Never D. Numerical data when significant outliers are present
A
Which equation corresponds to the expected value of an experiment with n samples, random variable x, probability P(x), confidence level c, and standard deviation s? A. ∑ x * P(x) B. ∑ x * s/c C. ∑ x/P(x) D. = (1-c)/2 * s/√n
A
Which of the following are NOT properties of the normal distribution? A. the mean, median, and mode are all equal. B. symmetric about the mean. C. total area under the curve is equal to 1. D. centered at 0 with standard deviation of 1.
A
Which of the following statistics is least impacted by outliers? A. Median B. Range C. Mean D. Variance E. Mode
A
The mean score on a standardized math exam is 72.6 the standard deviation is 10.5. Paul is told that the z-score of his exam score is 1.2. Is Paul's score above average or below average?
Above average
A mechanic is interested in when transmissions fail. She randomly selects eleven cars whose transmissions have failed. Ten of them had their transmissions fail between 150,000 to 200,000 miles. The single Chevy Spark examined, however, had its transmission fail at 10,000 miles. How will the mean compare to the median? A. Impossible to tell without further information B. Mean < Median C. Mean > Median D. Mean = Median
B
A randomly selected sample of size 19 has a mean of 3 and a standard deviation of 1. Assume the population is normally distributed. Which function finds the probability that t is less than 1.3? A. =T.DIST(1.3, 3, 1, TRUE) B. =T.DIST(1.3, 18, TRUE) C. =T.DIST(1- 1.3, 18, TRUE) D. =1 - T.DIST(1.3, 19, TRUE) E. =T.DIST(1.3 0, 1, TRUE) F. =T.DIST(1.3, 3, 1/SQRT(19), TRUE) G. = T.DIST(1.3, 19, FALSE) H. T.DIST(1.3 - 1, 3, 1, TRUE) I. =Z.DIST(1.3 3, 1, TRUE) J. =T.DIST(1.3, 19, TRUE) K. =1 - T.DIST(1.3, 3, 1, TRUE) L. = 1 - T.DIST(1.3, 18, TRUE) M. =T.DIST(1.3 - 1, 19, TRUE)
B
A synthetic fiber used in manufacturing carpet has tensile strength that is normally distributed with mean 75.0 psi and standard deviation 10.0 psi. For a sample of 100 fibers, we can calculate the probability that the sample mean is less than 71 psi using the excel command: A. =T.DIST() B. =NORM.DIST() C. =T.INV() D. =NORM.INV() E. =CONFIDENCE.T()
B
The Department of Education wishes to estimate the proportion of all college students who have a job off-campus. It surveyed 1600 randomly selected students 451 had such jobs. The population of interest to the Department of Education is: A. all college students B. all college students who have a job off campus. C. all 1600 students surveyed. D. the 451 students in the survey who have off-campus jobs. E. none of these answers.
B
The difference between the maximum and minimum value is called the A. set length B. range C. standard deviation D. variance E. median
B
The law of large numbers states that ________________. A. as more trials are undertaken, the expected value approaches 0. B. as the number of trials increases, the experimental probability approaches the theoretical probability. C. the larger the mean, the greater the standard deviation for an experiment. D. the theoretical mean is larger than the experimental mean.
B
What is the range of probabilities for an event A? A. 0 ≤ P(A) B. 0 ≤ P(A) ≤ 1 C. -∞ ≤ P(A) ≤ ∞ D. -1 ≤ P(A) ≤ 1
B
A cop measures the speeds of drivers on a highway. The average speed is 70 mph. However, a truck is struggling to go uphill and is driving 50 mph. What can the cop say about their z-score? A. It is positive. B. It is between 0 and 1. C. It is negative. D. Not enough information. E. It is 70 mph.
C
A professor wants to study the GPAs of students enrolled in all STAT 1222 classes at her university. She asks 15 randomly selected STAT 1222 students what their GPA is and finds the average is 3.65. What is the population? A. All STAT 1222 students anywhere B. Students enrolled at her university C. All students enrolled in STAT D. 1222 classes at her university E. The 15 randomly selected students
C
An economist samples 20 Fortune 500 companies and finds they have an average CEO salary of $11.5 million with a standard deviation of $2 million. She wants to know what t-value corresponds to a probability of 0.75. Which function finds this in Excel? A. =T.INV(0.75, 20) B. =T.DIST(0.75, 19, TRUE) C. =T.INV(0.75, 19) D. =T.DIST(0.75, 20, FALSE) E. =T.DIST(0.75, 20, TRUE) F. =T.DIST(0.75, 19, FALSE)
C
Assume that the resting pulse rate for healthy adults follow a normal distribution with a mean of 69 beats per minute and a standard deviation of 9.5 beats per minute. Adam is told that the z-score of his pulse rate is -0.5. How should this statement be interpreted? A. Exactly 5% of healthy adults have pulse rates less than Adam's pulse rate. B. Adam's pulse rate is about one half of a standard deviation above average. C. Adam's pulse rate is about one half of a standard deviation below average. D. Adam's pulse rate is above the mean. E. Adam should see a doctor because his pulse rate is unusually low.
C
If you are constructing a 95% confidence interval for a normally distributed population when your sample size is 10, what critical value should you use? A. z0.05 B. t0.025 C. t0.05 D. z0.025
C
Seven footprints were found at a crime scene. Their length was measured in inches and recorded in the table below: 9.25, 9.25, 9.4, 9.5, 9.6, 9.6, 9.6. If another footprint was found that was 9.3 in, what would happen to the median? A. It would decrease. B. It would increase. C. It wouldn't change. D. Impossible to tell without further information.
C
The amount of multivitamin gummies eaten by college students in a 1-month period is normally distributed with a mean of 25 and standard deviation of 3. Find the confidence interval for the mean amount of gummies eaten in a month by a random sample of twelve college students if the given error bound is 5. A. (25-3/√12, 25+3/√12) B. (22,28) C. (20,30) D. (25-15/√12, 25+15/√12)
C
The probability a person who reserved a trip on a 12-vehicle ferry will not arrive is 0.15. The ferry company makes 13 reservations for a particular trip, and we want to find the chance that all 13 vehicles show. What is a "success"? A. All 12 reservations not showing up B. A person who reserved a trip not showing up C. A person who reserved a trip showing up D. All 13 reservations not showing up E. All 12 reservations showing up F. All 13 reservations showing up
C
The probability that T takes on a value between -t0.05 and t0.05 is: A. 0.95 B. 0.80 C. 0.90 D. 0.05 E. 0.85
C
The score made by a particular student on a national standardized exam is the 65th percentile. This means that A. About 65% of all scores on the exam were higher than his. B. About 65% of all scores on the exam were lower than his. C. No answer text provided. D. His score is 65% of the average score. E. His score is the 65th best on the exam. F. He got about 65% of the answers correct.
C
A university wants to find out how undergraduate students feel about on-campus food sources. They randomly select 10 Freshmen, 10 Sophomores, 10 Junior, and 10 Seniors to fill out a survey. This is an example of _____ sampling.
Cluster
Two students want to know how many parties people at their university attend per month. They ask 10 people that are in their statistics class how many parties they attend. This is an example of _____ sampling.
Convenience
A geographer randomly selects twenty points in a county to study the elevation. One point is on a large hill while the other points are near water level. How does the mean compare to the median? A. Mean = Median B. Mean < Median C. Impossible to tell without further information D. Mean > Median
D
Cell phone bills for a city's residents have a mean of $63 and a standard deviation of $11. Random samples of 100 bills are drawn from this population, and the mean of each sample is found. What is the mean of the sampling distribution? A. 11 B. 0.11 C. 0.63 D. 63 E. 6.3
D
If A = {3, 6, 9, 10} and B = {3, 4, 5, 6}, what is A ∪ B? A. {4, 5, 9, 10} B. {3, 6} C. {3, 6, 9} D. {3, 4, 5, 6, 9, 10}
D
In a survey of 100 U.S. adults, 66 said that it is acceptable to check personal e-mail while at work. What is the sample proportion of failures? A. 1.52 B. 0.44 C. 0.66 D. 0.34
D
Suppose we are working within a normal distribution. Which function finds an event's value given the probability of an event? A. =NORM.DIST() B. =PROBABILITY() C. =STAND.DIST() D. =NORM.INV()
D
Suppose we are working within a normal distribution. Which function finds the cumulative probability of an event given that event's value? A. =STAND.NORM() B. =NORM.INV() C. =PROBABILITY() D. =NORM.DIST()
D
The probability that T takes on a value between -t0.10 and t0.10 is: A. 0.95 B. 0.05 C. 0.85 D. 0.80 E. 0.90
D
What is the z-score of a person whose LDL is one standard deviation above the mean? A. 90% B. 10% C. -1.0 D. 1.0 E. 10
D
Which of the following would NOT be an appropriate measure of central tendency when looking at incomes of a middle class neighborhood when one neighbor just sold their startup idea to Facebook for $1,000,000? A. Median B. Mode C. No other answer choice was an acceptable measure of central tendency D. Mean E. All other answer choices are acceptable measures of central tendency
D
A researcher wishes to estimate the average amount spent per person by visitors to a theme park. She takes a random sample of forty visitors and obtains an average of $28 per person. The population of interest is A. the amount of money spent per person. B. the forty selected visitors. C. theme park researchers. D. $28 per person. E. visitors to the theme park
E
In a random sample of 19 patients at a hospital's emergency department, the mean waiting time before seeing a medical professional was 23 min and the standard deviation was 11 min. Assume the waiting times are not normally distributed. Which distribution would this situation call for? A. z-distribution B. t-distribution C. no distribution can be used without applying the CLT D. more information is needed E. normal distribution
E
The mean monthly salary of a random sample of 20 college graduates under the age of 30 was found to be $1320 with a standard deviation of $677. Assume that the distribution of salaries for all college graduates under the age of 30 is normally distributed. Suppose a 90% confidence interval for the population mean of monthly salaries of all college graduates under the age of 30 was calculated. Which of the following would produce a narrower interval than the 90% confidence interval? A. A 95% confidence interval rather than a 90% confidence interval. B. A sample with a standard deviation of 1000 instead of 677. C. A sample of size 28 instead of 20. D. A sample of size 15 instead of 20. E. A sample with a standard deviation of 725 instead of 677.
E
The 54th percentile in a large data set is 98.6. Approximately what percentage of the observations are greater than 98.6?\ A. 98.6% B. 50% C, 1.4% D. 54% E. 46%
E. 46%
True or false?: Median and average are the same thing
False
What level of measurement is hair color?
Nominal
Is college class ranking nominal, ordinal, interval, or ratio?
Ordinal
What level of measurement is a military rank?
Ordinal
Managers at a hospital are interested in the length of stay (in days) of open-heart patients who underwent surgery within the last year. Thirty five open-heart surgery patients admitted to the hospital within the last year are selected. Is the average length of stay of all open-heart patients who underwent surgery in the last year the population, sample, parameter, statistic, and variable in this problem?
Parameter
Managers at a hospital are interested in the length of stay (in days) of open-heart patients who underwent surgery within the last year. Thirty five open-heart surgery patients admitted to the hospital within the last year are selected. Is all open-heart patients who underwent surgery in the last year the population, sample, parameter, statistic, and variable in this problem?
Population
Identify the following measure as either quantitative or qualitative: The genders of the first 40 newborns in a hospital one year.
Qualitative
Identify the following measure as either quantitative or qualitative: The 30 high-temperature readings of the last 30 days.
Quantitative continuous
Identify the following measure as either quantitative or qualitative: The age (in years) of 20 randomly selected fashion model.
Quantitative discrete
Identify the the following as either qualitative, quantitative discrete, or qualitative continuous: number of students responding to a survey about their names.
Quantitative discrete
What level of rank is distance?
Ratio
Managers at a hospital are interested in the length of stay (in days) of open-heart patients who underwent surgery within the last year. Thirty five open-heart surgery patients admitted to the hospital within the last year are selected. Is the thirty five open-heart patients who underwent surgery in the last year the population, sample, parameter, statistic, and variable in this problem?
Sample
A student organization has 55 members. A table of random numbers is used to select a sample of 5. This is an example of _____ sampling.
Simple random
Managers at a hospital are interested in the length of stay (in days) of open-heart patients who underwent surgery within the last year. Thirty-five open-heart surgery patients admitted to the hospital within the last year are selected. Is the average length of stay of the thirty-five selected open-heart patients the population, sample, parameter, statistic, and variable in this problem?
Statistic
There are 7 sections of an introductory statistics course. A random sample of 3 sections is chosen, and all students in those sections are asked to fill out an evaluation of the text book. This is an example of _____ sampling.
Stratified
What is the population?
Students diagnosed with ADD
The mathematics department wants to know how many hours a week students spend studying for math classes. They take the full list of students enrolled in math classes, and choose every 25th student from the list. This is an example of _____ sampling.
Systematic
A statistician wants to find the probability that a z score is between 1 and 2.5. Which of these functions gives the probability? A. =NORM.DIST(2.5, 0, 1, TRUE)- NORM.DIST(1, 0, 1, TRUE) B. =NORM.DIST(2.5, 0, 1, TRUE) + NORM.DIST(1, 0, 1, TRUE) C. =NORM.DIST(2.5 - 1, 0, 1, FALSE) D. Not enough information - the n is not given. E. =NORM.DIST(2.5 - 1, 0, 1, TRUE) F. Not enough information - the mean and standard deviation are not given.
a
A survey shows that people use cell phones an average of 1.5 years with a standard deviation of 0.5 years. A user is randomly selected. If cell phone use is normally distributed, we can use Excel to calculate the probability that the randomly selected user uses their phone for less than 1 year with the function: A. =NORM.DIST(1, 1.5, 0.5, TRUE) B. =1- NORM.INV(1, 1.5, 0.5) C. =NORM.INV(1, 1.5, 0.5) D. =1 - NORM.DIST(1, 1.5, 0.5, FALSE) E. =1 - NORM.DIST(1, 1.5, 0.5, TRUE)
a
Find the area to the right of a z-score of z = -0.85. A. =1- NORM.DIST(-0.85, 0, 1, TRUE) B. Impossible. Z scores must be positive. C. =NORM.DIST(1-(-0.85), 0, 1, TRUE) D. Not enough information given. E. =NORM.DIST(-0.85, 0, 1, TRUE)
a
Find the cumulative area that corresponds to a z-score of 0.24 A. =NORM.DIST(0.24, 0, 1, TRUE) B. Not enough information is given C. =NORM.DIST(0.76, 0, 1, TRUE) D. =NORM.INV(0.24, 0, 1)
a
Food scientists conduct a survey of randomly selected individuals to find out the percentage of people who think a hot dog is a sandwich. What distribution should they use to make a confidence interval for the population proportion? A. z distribution B. They should use either a z or t distribution depending on how big their sample size is. C. t distribution D. p distribution E. c distribution
a
The more samples a researcher takes, the _______________ the confidence interval. A. less wide B. less normalized C. wider D. more uncertain
a
What happens to the mean and standard deviation of the distribution of sample means as the size of the sample increases? A. The mean of the sample means stays constant and the standard error decreases. B. The mean of the sample means decreases and the standard error increases. C. The mean of the sample means increases and the standard error stays constant. D. The mean of the sample means decreases and the standard error decreases. E. The mean of the sample means increases and the standard error decreases. F. The mean of the sample means stays constant and the standard error increases. G. The mean of the sample means increases and the standard error increases. H. The mean of the sample means decreases and the standard error stays constant. I. The mean of the sample means stays constant and the standard error stays constant.
a
Which of the following are NOT properties of the normal distribution? A. centered at 0 with standard deviation of 1. B. total area under the curve is equal to 1. C. the mean, median, and mode are all equal. D. symmetric about the mean.
a
Which of the following random variables is discrete? A. the number of heads tossed on four distinct coins B. the mass of a test cylinder of concrete C. the time spent waiting for a bus at the bus stop D. the amount of water traveling over a waterfall in one minute
a
An ornithologist wants to know the probability that a randomly selected male kakapo (owl parrot) is between 3 and 7 lb. A sample of 39 males showed their mean weight is 4.5 lb with a standard deviation of 2 lb. What function gives this probability? A. =NORM.DIST(7, 4.5, 2, TRUE) - NORM.DIST(3, 4.5, 2, TRUE) B. =NORM.DIST(7-3, 4.5, 2, TRUE) C. =NORM.DIST(7, 4.5, 2/SQRT(39), TRUE) + NORM.DIST(3, 4.5, 2/SQRT(39), TRUE) D. =NORM.DIST(7, 4.5, 2/SQRT(39), TRUE) - NORM.DIST(3, 4.5, 2/SQRT(39), TRUE) E. =T.DIST(7, 4.5, 2, TRUE) - T.DIST(3, 4.5, 2, TRUE)
answer needed
Which of the following functions finds the probability that t is between -1.2 and 0.5 for a sample size of 12? A. =T.DIST( 0.5- 1.2), 12, FALSE) B. =T.DIST(0.5, 12, FALSE) - T.DIST(-1.2, 12, FALSE) C. =T.DIST(-1.2, 12, TRUE) - T.DIST(0.5, 11, TRUE) D. =T.DIST(0.5, 11, TRUE) - T.DIST(-1.2, 11, TRUE) E. =T.DIST(0.5, 12, TRUE) - T.DIST(-1.2, 12, TRUE) F. =T.DIST( 0.5 - (1.2), 12, TRUE) G. =T.DIST( 0.5 - (1.2), 11, FALSE)
answer needed
A government agency was charged by the legislature with estimating the length of time it takes citizens to fill out various forms. The agency generated an 85% confidence interval, a 90% confidence interval, and a 99% confidence interval, all of which are listed below. Which one is the 90% confidence interval? A. (12.49, 13.11) B. (12.60, 13.00) C. (12.63, 12.97)
b
A z-score of 1 means that A. non-negative. B. a value is one standard deviation away from the mean. C. very unusual. D. a value is one variance away from the mean
b
The standard normal distribution has a mean of ____ and a standard deviation of ______. A. x̄, s/√n B. 0,1 C. μ, σ^2 D. 1,0
b
To calculate the probability that an event A is between b and c, where b<c, you use the formula: A. P(b ≤ A ≤ c) = c-b/n where n is the total number of possible outcomes B. P(b ≤ A ≤ c) = P(A ≤ c) - P (A ≤ b) C. P (b ≤ A ≤ c) = P(c) - P(b) D. P(b ≤ A ≤ c) = P(b) + P(c) - P ( b u c)
b
When estimating a population parameter, a point estimate is A. the population mean. B. a statistic that estimates a population parameter. C. a range of possible values for the population parameter. D. always equal to the population value.
b
Which formula gives the standard deviation for a binomial distribution? A. σ = np B. σ= √npq C. s= σn D. s=xpn
b
If, after you obtain a 95% confidence interval , you find it to be too narrow, which of the following steps can you take to increase the width (i.e. E gets larger) of the confidence interval? (choose all that apply) A. Construct a 99% confidence interval instead of a 95% one. B. Construct a 90% confidence interval instead of a 95% one. C. Re-do the 95% confidence interval using a smaller sample size. D. Re-do the 95% confidence interval using a larger sample size.
b, c
A sample space is _______________________. A. the results of a specific sample in an experiment. B. the amount of samples taken. C. the set of all possible outcomes in an experiment. D. the distribution of sample means.
c
Which of the following is NOT a property of the standard normal distribution? A. the total area under the curve is equal to 1. B. symmetric about the mean. C. uniform in shape. D. centered at 0 with standard deviation of 1. E. bell-shaped
c
Which of the following is a possible probability for an event A? A. P(A) = -0.50 B. P(A) = 1.10 C. P(A) = 0 D. P(A) = 112%
c
You roll a fair six-sided die. Find the probability of event C: rolling a number less than 5. A. P(C) = 2/6 B. P(C) = 3/6 C. P(C) = 4/6 D. P(C) = 1/6 E. P(C) = ⅚
c
A soda company wants to estimate the population proportion of people who drink soda with confidence level c, so they take a sample of 45 people. What equation gives their critical value? A. =NORM.DIST(c, 0, 1, TRUE) B. =NORM.DIST((1-c)/2, 0, 1, FALSE) C. =NORM.INV(c, 0, 1, TRUE) D. =NORM.INV((1-c)/2, 0, 1)
d
A survey shows that people use cell phones an average of 1.5 years with a standard deviation of 0.5 years. A user is randomly selected. If cell phone use is normally distributed, we can use Excel to calculate the probability that the randomly selected user uses their phone for more than 1 year with the function: A. =1- NORM.INV(1, 1.5, 0.5) B. =NORM.INV(1, 1.5, 0.5) C. =NORM.DIST(1, 1.5, 0.5, FALSE) D. =1 - NORM.DIST(1, 1.5, 0.5, TRUE) E. =NORM.DIST(1, 1.5, 0.5, TRUE)
d
A z-score of 1 means that _____ A. very unusual. B. non-negative. C. a value is one variance away from the mean. D. a value is one standard deviation away from the mean.
d
All of the following are measures of central tendency EXCEPT: A. median B. mean C. mode D. standard deviation
d
If a population is heavily skewed to the right, can we use the central limit theorem? A. No, the central limit theorem does not adjust for skew. Another method is needed. B. Yes, we can use the central limit theorem with any population. C. No, we must use the t-distribution. D. Yes, if enough samples are taken
d
The square root of the (a) is called the (b) A. standard deviation, variance B. mean, median C. median, mean D. variance, standard deviation
d
The training heart rates of all athletes are normally distributed, with mean 135 bpm and standard deviation 18 bpm. Random samples of 4 are drawn, and the mean of each is found. Find the mean of the sampling distribution. A. 135/18 B. 135/√4 C. √135/4 D. 135
d
The training heart rates of all athletes are normally distributed, with mean 135 bpm and standard deviation 18 bpm. Random samples of 4 are drawn, and the mean of each is found. Find the standard error of the mean A. 18/4 B. 18 C. 18^2 D. 18/√4 E. √18
d
To find the z-score corresponding to a right tail area of 0.25 in Excel we would use: A. =T.INV(0.25, 0, 1) B. =NORM.DIST(0.25, 0, 1, TRUE) C. =NORM.DIST(0.25, 0, 1, FALSE) D. =NORM.INV(1-0.25, 0, 1) E. =NORM.INV(0.25, 0, 1)
d
Which formula gives the mean for a binomial distribution? A. μ=npq B. μ=½x C. μ=xn D. μ=np
d
Which of the following is a possible probability for an event A? A. P(A) = -0.50 B. P(A) = 112% C. P(A) = 1.10 D. P(A) = 0
d
Which of the following random variables is discrete? A. the mass of a test cylinder of concrete B. the amount of water traveling over a waterfall in one minute C. the time spent waiting for a bus at the bus stop D. the number of heads tossed on four distinct coins
d
You roll a fair 6 sided die. Find the probability of event B rolling a 4. A. 0 B. 3/6 C. 2/6 D. ⅙ E. 4/6
d
Suppose that 40% of all Charlotte voters favor a particular political candidate. You take a poll of 100 Charlotte voters. If the random variable X denotes the number of voters in your sample who favor the candidate, then the mean of X is: A. 24 B. 5 C. 38 D. 60 E. 40-
e
What happens to the mean and standard deviation of the distribution of sample means as the size of the sample decreases? A. The mean of the sample means stays constant and the standard error decreases. B. The mean of the sample means increases and the standard error increases. C. The mean of the sample means increases and the standard error stays constant. D. The mean of the sample means decreases and the standard error decreases. E. The mean of the sample means increases and the standard error decreases. F. The mean of the sample means stays constant and the standard error increases. G. The mean of the sample means decreases and the standard error stays constant. H. The mean of the sample means decreases and the standard error increases. I. The mean of the sample means stays constant and the standard error stays constant.
f
True or false?: The standard normal distribution has more probability in its tails than the t distribution.
false
Is temperature in degrees Celsius nominal, ordinal, interval, or ratio?
interval
What level of measurement is temperature?
interval
The graph is skewed left and therefore we expect that the mean is _____ than the median.
lower than
Is religious preference nominal, ordinal, interval or ratio?
nominal
Identify the following as either qualitative, quantitative discrete, or quantitative continuous: Body temperatures in oC.
quantitative continuous
Is weight in lb nominal, ordinal, interval or ratio?
ratio
Which of the following is the symbol for sample standard deviation?
s
With all other things kept constant, an increased _____ _____ will decrease the width of a confidence interval.
sample size
The graph is symmetric and therefore we expect that the mean is _____ than the median.
the same as
Managers at a hospital are interested in the length of stay (in days) of open-heart patients who underwent surgery within the last year. Thirty five open-heart surgery patients admitted to the hospital within the last year are selected. Is the length of hospital stay the population, sample, parameter, statistic, and variable in this problem?
variable
What is the symbol for sample mean?
x̅
What is the symbol for population mean?
μ
Which is the symbol for population standard deviation?
σ
What is the symbol for population variance?
σ2
