1. A continuous probability distribution represents a random variable
A. that's best described in a histogram.
B. that has a definite probability for the occurrence of a given integer.
C. having an infinite number of outcomes that may assume any number of values within an interval.
D. having outcomes that occur in counting numbers.
2. Find the z-score that determines that the area to the right of z is 0.8264.
3. The area under the normal curve extending to the right from the midpoint to z is 0.17. Using the standard normal table on the textbook's back end sheet, identify the relevant z value.
4. A new car salesperson knows that she sells a car to one customer out of 20 who enter the showroom. Find the probability that she'll sell a car to exactly two of the next three customers.
5. For each car entering the drive-through of a fast-food restaurant, x = the number of occupants. In this study, x is a
A. discrete random variable.
B. dependent event.
C. continuous quantitative variable.
D. joint probability.
6. The Burger Bin fast-food restaurant sells a mean of 24 burgers an hour and its burger sales are normally distributed. The standard deviation is 6. What is the probability that the Burger Bin will sell 12 to 18
burgers in an hour?
7. If event A and event B are mutually exclusive, P(A or B) =
A. P(A) â€“ P(B).
B. P(A + B).
C. P(A) + P(B) â€“ P(A and B).
D. P(A) + P(B).
8. The Burger Bin fast-food restaurant sells a mean of 24 burgers an hour and its burger sales are normally distributed. If hourly sales fall between 24 and 42 burgers 49.85% of the time, the standard deviation is _______ burgers.
9. The possible values of x in a certain continuous probability distribution consist of the infinite number of values between 1 and 20. Solve for P(x = 4).
10. An apartment complex has two activating devices in each fire detector. One is smoke-activated and has a probability of .98 of sounding an alarm when it should. The second is a heat-sensitive activator and has a probability of .95 of operating when it should. Each activator operates independently of the other. Presume a fire starts near a detector. What is the probability that both activating devices will work properly?
11. Assume that an event A contains 10 observations and event B contains 15 observations. If the intersection of events A and B contains exactly 3 observations, how many observations are in the union of these two events?
12. If the probability that an event will happen is 0.3, what is the probability of the event's complement?
13. What is the value of ?
14. The probability of an offender having a speeding ticket is 35%, having a parking ticket is 44%, having both is 12%. What is the probability of an offender having either a speeding ticket or a parking ticket or both?
15. Which of the following is a discrete random variable?
A. The number of three-point shots completed in a college basketball game
B. The time required to drive from Dallas to Denver
C. The weight of football players in the NFL
D. The average daily consumption of water in a household
16. Consider an experiment that results in a positive outcome with probability 0.38 and a negative outcome with probability 0.62. Create a new experiment consisting of repeating the original experiment 3 times. Assume each repetition is independent of the others. What is the probability of three successes?
17. Each football game begins with a coin toss in the presence of the captains from the two opposing
teams. (The winner of the toss has the choice of goals or of kicking or receiving the first kickoff.) A
particular football team is scheduled to play 10 games this season. Let x = the number of coin tosses that
the team captain wins during the season. Using the appropriate table in your textbook, solve for P(4 â‰¤ x â‰¤8).
End of exam
18. Approximately how much of the total area under the normal curve will be in the interval spanning 2
standard deviations on either side of the mean?
19. A credit card company decides to study the frequency with which its cardholders charge for items from a certain chain of retail stores. The data values collected in the study appear to be normally distributed with a mean of 25 charged purchases and a standard deviation of 2 charged purchases. Out of the total number of cardholders, about how many would you expect are charging 27 or more purchases in this study?
20. From an ordinary deck of 52 playing cards, one is selected at random. What is the probability that the selected card is either an ace, a queen, or a three?
1. In sampling without replacement from a population of 900, it's found that the standard error of the mean, , is only two-thirds as large as it would have been if the population were infinite in size. What is the approximate sample size?
2. What is the rejection region for a two-tailed test when Î± = 0.05?
A. |z | > 2.575
B. z > 2.575
C. |z | > 1.96
D. |z | > 1.645
3. A mortgage broker is offering home mortgages at a rate of 9.5%, but the broker is fearful that this value is higher than many others are charging. A sample of 40 mortgages filed in the county courthouse shows an average of 9.25% with a standard deviation of 8.61%. Does this sample indicate a smaller average? Use Î± = 0.05 and assume a normally distributed population.
A. No, because the test statistic is â€“1.85 and falls in the rejection region.
B. No, because the test statistic falls in the acceptance region.
C. Yes, because the test statistic is greater than â€“1.645.
D. Yes, because the sample mean of 9.25 is below 9.5.
4. What sample size is required from a very large population to estimate a population proportion within 0.05 with 95% confidence? Don't assume any particular value for p.
5. A federal auditor for nationally chartered banks, from a random sample of 100 accounts, found that the average demand deposit balance at the First National Bank of Arkansas was $549.82. If the auditor needed a point estimate for the population mean for all accounts at this bank, what should he use?
A. There's no acceptable value available.
B. The average of $54.98 for this sample
C. The average of $549.82 for this sample
D. The auditor should survey the total of all accounts and determine the mean.
6. The commissioner of the state police is reported as saying that about 10% of reported auto thefts involve owners whose cars haven't really been stolen. What null and alternative hypotheses would be appropriate in evaluating this statement made by the commissioner?
A. H0: p > 0.10 and H1: p â‰¤ 0.10
B. H0: p â‰¥ 0.10 and H1: p < 0.10
C. H0: p â‰¤ 0.10 and H1: p > 0.10
D. H0: p = 0.10 and H1: p â‰ 0.10
7. To schedule appointments better, the office manager for an ophthalmologist wants to estimate the average time that the doctor spends with each patient. A random sample of 49 is taken, and the sample mean is 20.3 minutes. Assume that the office manager knows from past experience that the standard deviation is 14 minutes. She finds that a 95% confidence interval is between 18.3 and 22.3 minutes. What is the point estimate of the population mean, and what is the confidence coefficient?
A. 18.3, 0.95
B. 20.3, 0.95
C. 18.3, 95%
D. 20.3, 95%
8. The power of a test is the probability of making a/an _______ decision when the null hypothesis is _______.
A. correct, false
B. correct, true
C. incorrect, true
D. incorrect, false
9. A human resources manager wants to determine a confidence interval estimate for the mean test score for the next office-skills test to be given to a group of job applicants. In the past, the test scores have been normally distributed with a mean of 74.2 and a standard deviation of 30.9. Determine a 95% confidence interval estimate if there are 30 applicants in the group.
A. 68.72 to 79.68
B. 64.92 to 83.48
C. 13.64 to 134.76
D. 63.14 to 85.26
10. If the level of significance (Î±) is 0.005 in a two-tail test, how large is the nonrejection region under the curve of the t distribution?
11. Consider a null hypothesis stating that the population mean is equal to 52, with the research hypothesis that the population mean is not equal to 52. Assume we have collected 38 sample data from which we computed a sample mean of 53.67 and a sample standard deviation of 3.84. Further assume the sample data appear approximately normal. What is the test statistic?
12. A researcher wants to carry out a hypothesis test involving the mean for a sample of n = 20. While the true value of the population standard deviation is unknown, the researcher is reasonably sure that the population is normally distributed. Given this information, which of the following statements would be correct?
A. The researcher should use the z-test because the population is assumed to be normally distributed.
B. The t-test should be used because the sample size is small.
C. The t-test should be used because Î± and Î¼ are unknown.
D. The researcher should use the z-test because the sample size is less than 30.
13. What is the purpose of sampling?
A. To estimate a target parameter of the population
B. To achieve a more accurate result than can be achieved by surveying the entire population
C. To create a point estimator of the population mean or proportion
D. To verify that the population is approximately normally distributed
14. If a teacher wants to test her belief that more than five students in college classes typically receive A as a grade, she'll perform _______-tail testing of a _______.
A. two, mean
B. two, proportion
C. one, proportion
D. one, mean
15. Which of the following statements about p-value testing is true?
A. P-value testing uses a predetermined level of significance.
B. P-value testing applies only to one-tail tests.
C. The p-value is the lowest significance level at which you should reject H0.
D. The p represents sample proportion.
16. For 1996, the U.S. Department of Agriculture estimated that American consumers would have eaten, on average, 2.6 pounds of cottage cheese throughout the course of that year. Based on a longitudinal studyof 98 randomly selected people conducted during 1996, the National Center for Cottage Cheese Studies found an average cottage cheese consumption of 2.75 pounds and a standard deviation of s = 14 ounces.
Given this information, which of the following statements would be correct concerning a two-tail test at the 0.05 level of significance?
A. We can conclude that the average cottage cheese consumption in America isn't 2.6 pounds per person per year.
B. We can conclude that we can't reject the claim that the average cottage cheese consumption in America is 2.6 pounds per person per year.
C. We can conclude that the average cottage cheese consumption in America is at least 0.705 pound more or less than 2.75 pounds per person per year.
D. We can conclude that the average cottage cheese consumption in America is actually 2.75 pounds per person per year.
17. A portfolio manager was analyzing the price-earnings ratio for this year's performance. His boss said that the average price-earnings ratio was 20 for the many stocks that his firm had traded, but the portfolio manager felt that the figure was too high. He randomly selected a sample of 50 price-earnings ratios and found a mean of 18.17 and a standard deviation of 4.60. Assume that the population is normally distributed, and test at the 0.01 level of significance. Which of the following is the correct decision rule for
the manager to use in this situation?
A. Because 2.81 is greater than 2.33, reject H0. At the 0.01 level, the sample data suggest that the average price-earnings ratio for the stocks is less than 20.
B. If t > 2.68 or if t < â€“2.68, reject H0.
C. Because â€“2.81 falls in the rejection region, reject H0. At the 0.01 level, the sample data suggest that the average priceearnings ratio for the stocks is less than 20.
D. If z > 2.33, reject H0.
18. In a simple random sample from a population of several hundred that's approximately normally distributed, the following data values were collected.
68, 79, 70, 98, 74, 79, 50, 102, 92, 96
Based on this information, the confidence level would be 90% that the population mean is somewhere between
A. 73.36 and 88.24.
B. 65.33 and 95.33.
C. 69.15 and 92.45.
D. 71.36 and 90.24.
19. In a criminal trial, a Type II error is made when a/an
A. guilty defendant is convicted.
B. guilty defendant is acquitted.
C. innocent person is acquitted.
D. innocent person is convicted.
20. What is the primary reason for applying a finite population correction coefficient?
A. When the sample is a very small portion of the population, the correction coefficient is required.
B. If you don't apply the correction coefficient, your confidence intervals will be too narrow, and thus overconfident.
C. If you don't apply the correction coefficient, you won't have values to plug in for all the variables in the confidence interval formula.
D. If you don't apply the correction coefficient, your confidence intervals will be too broad, and thus less useful in decision making.
|Due By (Pacific Time)||08/02/2015 11:30 am|
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