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Review Questions
Test 2: MSIT 3000 1. A market research group compared the prices of 1. A market research group compared the prices of groceries at Kroger and Publix. Prices of 50 items were obtained from both Kroger and Publix (the same items at each store). Which test should be used to determine if the two stores have different prices?
A. Onetailed test of two independent means
B. Twotailed test of two independent means
C. Onetailed paired ttest
D. Twotailed paired ttest 2. A financial analyst computed the assets to 2. A financial analyst computed the assets to liability ratio for 68 “healthy” and 33 “failing” firms. To see if this ratio is higher for healthy firms (Group 1), which hypotheses should be tested?
A. H0: µ1 − µ2 = 0; HA: µ1 − µ2 > 0 B. H0: µ1 − µ2 = 0; HA: µ1 − µ2 < 0
C. H0: µ1 − µ2 = 0; HA: µ1 − µ2 ≠ 0
D. H0: µD = 0; HA: µD > 0
E. H : µ = 0; H : µ ≠ 0 3. What is the test conclusion for α = 0.05? 3. What is the test conclusion for = 0.05?
tstatistic = 1.75 with df = 212, Pvalue = 0.07 A. Sufficient evidence to conclude that healthy firms have the same asset to liability ratios
B. Insufficient evidence to claim that healthy firms have the same asset to liability ratios
C. Insufficient evidence to claim that healthy firms have higher asset to liability ratios 4. Would 0 be included in the 95% confidence 4. Would 0 be included in the 95% confidence interval? A. 0 is included in the 95% confidence interval
B. 0 is not included in the 95% confidence interval
C. Insufficient evidence to say if it is inside or not 5. You don’t claim a difference, but in fact there is 5. You don’t claim a difference, but in fact there is a difference between healthy and failed firms. Which type of error did you make? A. Type I error
B. Type II error
C. No error 6. Suppose the average house price in a suburb is $350,000 with a standard deviation of $50,000. If a sample of 100 houses is taken, what is the probability the average house price will be less than $360,000? A. 0.5792
B. 0.9772
C. 0.4208
D. 0.0228 7. Suppose the average house price in a suburb is 7. Suppose the average house price in a suburb is $350,000 with a standard deviation of $50,000. House prices are known to be skewed. If a sample of 100 houses is taken, will the nearly Normal condition be met?
A. Yes the nearly Normal condition will be satisfied
B. No the nearly Normal condition will not be satisfied
C. Not possible to say without seeing a graph of the data 8. Dave will only buy a car if it can be shown to have an average fuel efficiency greater than 30 mpg. A sample of 45 test drives yield an average of 32 mpg with standard error of 0.955. Which hypotheses should Dave test? A. H0: µ = 32; HA: µ > 32
B. H0: µ = 30; HA: µ > 32 C. H0: µ = 30; HA: µ ≠ 30
D. H0: µ = 30; HA: µ > 30 9. Dave will only buy a car if it can be shown to have an average fuel efficiency greater than 30 mpg. A sample of 45 test drives yield an average of 32 mpg with standard error of 0.955. What is the test statistic?
A. z = 2.094
B. z = −2.094
C. t = 2.094
D. t = −2.094 10. Dave will only buy a car if it can be shown to have an average fuel efficiency greater than 30 mpg. A sample of 45 test drives yield an average of 32 mpg with standard error of 0.955. What is the Pvalue?
A. 0.021
B. 0.042
C. 0.018
D. 0.036 11. Dave will only buy a car if it can be shown to have an average fuel efficiency greater than 30 mpg. A sample of 45 test drives yield an average of 32 mpg with standard error of 0.955. What is the conclusion for α = 0.05?
= 0.05?
A. Sufficient evidence to claim the average fuel efficiency is equal to 30 mpg
B. Sufficient evidence to claim the average fuel efficiency is more than 30 mpg
C. Insufficient evidence to claim the average fuel efficiency is equal to than 30 mpg
D. Insufficient evidence to claim the average fuel efficiency is more than 30 mpg 12. Dave thought the average fuel efficiency was more than 30 mpg so be bought the car, but in reality the fuel efficiency was equal to 30 mpg. Which type of error did Dave make? A. Type I error
B. Type II error
C. No error 13. Dave will only buy a certain car if it can be shown to have an average fuel efficiency greater than 30 mpg. In general (not just this sample), which would make it easier for Dave to buy the car: α = 0.05 or α = 0.10? = 0.05 or = 0.10? A. Easier to buy the car if α = 0.05 = 0.05
B. Easier to buy the car if α = 0.10 = 0.10
C. Doesn’t make a difference 14. Dave will only buy a certain car if it can be shown to have an average fuel efficiency greater than 30 mpg. A sample of 45 test drives yield an average of 32 mpg with standard error of 0.955. The Pvalue for the hypothesis test was found to be 0.021. What does this Pvalue mean? A. The probability is 0.021 that the true mean equals 30 mpg
B. The probability is 0.021 that the true mean is different from 30 mpg.
C. The probability is 0.021 of getting a sample mean of 32 mpg or higher, if the true mean equals 30 mpg. 15. A sample of 30 randomly chosen students reveal an average commuting time of 15 minutes with a standard deviation of 5 minutes. Construct a 95% confidence interval for the average student commuting time.
A. (4.78, 25.2) B. (5.2, 24.8) C. (13.21, 16.79) D. (13.13, 16.87) 16. What is the meaning of this 95% confidence interval? A. 95% of students have a commuting time within this interval B. With 95% confidence, a randomly chosen student will have a commuting time within this interval C. With 95% confidence, this interval will contain the true average commuting time
D. With 95% confidence, this interval will contain the sample average commuting time 17. If a 99% interval were constructed instead of 95%, what would happen to the margin of error? A. The margin of error would increase B. The margin of error would decrease
C. The margin of error would stay the same 18. The school board claims the average commuting time is 10 minutes. Based on the 95% confidence interval of (13.13, 16.87), what is the conclusion of the hypothesis test, α = 0.05? A. Sufficient evidence to claim the average commuting time is equal to 10 minutes.
B. Sufficient evidence to claim the average commuting time is different from 10 minutes.
C. Insufficient evidence to claim the average commuting time is equal to 10 minutes.
D. Insufficient evidence to claim the average commuting time is different from 10 minutes. 19. What sample size is required to estimate the true average commuting time to within 1 minute, with 95% confidence? The standard deviation of commuting times is 5 minutes. A. 9
B. 10
C. 96
D. 97 20. A survey of 250 restaurant customers found 20. A survey of 250 restaurant customers found that 180 were repeat customers. Prior to constructing a 90% confidence interval, what is the standard error of the sample proportion? A. 0.72
B. 0.0284
C. 0.0467
D. 0.0557 21. A survey of 250 restaurant customers found 21. A survey of 250 restaurant customers found that 180 were repeat customers. Prior to constructing a 90% confidence interval, what is the margin of error to estimate the true proportion of repeat customers?
A. 0.72
B. 0.0284
C. 0.0467
D. 0.0557 22. A survey of 250 restaurant customers found 22. A survey of 250 restaurant customers found that 180 were repeat customers. What is the 90% confidence interval for the true proportion of repeat customers? A. (0.673, 0.767)
B. (0.664, 0.776)
C. (0.647, 0.793)
D. (0.692, 0.748) 23. A restaurant would like to estimate the true 23. A restaurant would like to estimate the true roportion of repeat customers to within 0.02, with 99% confidence. What sample size should it use? A. 2401
B. 2402
C. 4147
D. 4148 24. A restaurant finds a 95% confidence interval 24. A restaurant finds a 95% confidence interval for the true proportion of repeat customers to be (0.76, 0.84). What is the margin of error in using the sample proportion to estimate the true proportion?
A. 0.04
B. 0.08
C. 0.05
D. 0.10 25. A restaurant finds a 95% confidence interval 25. A restaurant finds a 95% confidence interval for the true proportion of repeat customers to be (0.76, 0.84). A critic claims the proportion of repeat customers is 0.82. What is the conclusion of the hypothesis test to determine if the true proportion is different from 0.82?
A. Sufficient evidence the true proportion is equal to 0.82
B. Sufficient evidence the true proportion is different from 0.82 C. Insufficient evidence the true proportion is equal to 0.82
D. Insufficient evidence the true proportion is different from 0.82 26. A restaurant finds a 95% confidence interval 26. A restaurant finds a 95% confidence interval for the true proportion of repeat customers to be (0.76, 0.84). A critic claims the proportion of repeat customers is 0.88. What is the conclusion of the hypothesis test to determine if the true proportion is different from 0.88?
A. Sufficient evidence the true proportion is equal to 0.88
B. Sufficient evidence the true proportion is different from 0.88 C. Insufficient evidence the true proportion is equal to 0.88
D. Insufficient evidence the true proportion is different from 0.88 27. A college president claims 35% of students plan to study abroad. A survey of 150 students revealed 45 who planned to study abroad. Which ypotheses should be tested to see if the president’s prediction is correct?
A. H0: p = 0.3; HA: p ≠ 0.3
B. H0: p = 0.3; HA: p > 0.3
C. H0: p = 0.3 ; HA: p = 0.35
D. H0: p = 0.35; HA: p < 0.35
E. H : p = 0.35 ; H : p ≠ 0.35 28. A college president claims 35% of students plan to study abroad. A survey of 150 students revealed 45 who planned to study abroad. What is the test statistic? A. z = −1.28
B. z = 1.28
C. z = −1.34
D. z = 1.34 29. A college president claims 35% of students plan to study abroad. A survey of 150 students revealed 45 who planned to study abroad. What is the Pvalue? A. 0.0906
B. 0.0993
C. 0.1812
D. 0.1986 30. A college president claims 35% of students plan to study abroad. A survey of 150 students revealed 45 who planned to study abroad. What is the test conclusion for α = 0.10?
= 0.10? A. Insufficient evidence the president is right
B. Insufficient evidence the president is wrong
C. Sufficient evidence the president is right
D. Sufficient evidence the president is wrong 31. A college president claims 35% of students plan to study abroad. A survey of 150 students revealed 45 who planned to study abroad. Based on the hypothesis test Pvalue of 0.1986, what is true for a 90% confidence interval: A. The 90% confidence interval contains 0.35
B. The 90% confidence interval does not contain 0.35
C. Not possible to say without constructing the interval 32. Suppose the true proportion of students who own credit cards is 85%. If a sample of 120 randomly chosen students is taken, what is the probability at least 108 have a credit card? A. 0.9375
B. 0.9661
C. 0.0625
D. 0.0339 33. An electronics store conducts a survey of 15 randomly chosen people, and finds that 9 already have a smartphone. Are the conditions met for constructing a 95% confidence interval? A. No, the randomization condition is not met.
B. No, the 10% condition is not met.
C. No, the 10 expected successes/failures condition is not met.
D. Yes, all the conditions are met. Answers 1) D 2) A 3) C 4) A 5) B 6) B 7) A 8) D 9) C 10) A 11) B 12) A 13) B 14) C 15) D 16) C 17) A 18) B 19) D 20) B 21) C 22) A 23) D 24) A 25) D 26) B 27) E 28) A 29) D 30) B 31) A 32) C 33) C ...
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 Fall '11
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 B., c., Dave, insufficient evidence, average fuel efficiency

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