1. Multiple Choice Practice Chapter 23

2. A city representative claims that the policemen in the city earn an average of $52,000 per year. The local paper believes that the mean salary is less for the beat cops. A random sample of 20 beat cops are surveyed to find an mean salary of $51,300 with a standard deviation of $1900. What are the correct hypotheses? A) H 0 :  = 51,300 H A :  > 51,300 B) H 0 :  = 52,000 H A :  = 51,300 C) H 0 :  = 52,000 H A :  < 51,300 D) H 0 :  = 52,000 H A :  < 52,000 1.

3. A city representative claims that the policemen in the city earn an average of $52,000 per year. The local paper believes that the mean salary is less for the beat cops. A random sample of 20 beat cops are surveyed to find an mean salary of $51,300 with a standard deviation of $1900. Which are the test statistic and p-value for this test? A) t = –0.368 ; p-value > 0.25 B) t = –1.65 ; 0.01 < p-value < 0.05 C) t = –1.65 ; 0.05 < p-value < 0.10 D) t = 1.65 ; 0.05 < p-value < 0.10 2.

4. Compare the standard normal distribution to the t-distribution. Which of the statements are true? I.Both have a center of 0 (standard deviations) II.Both are symmetrical and bell-shaped III.Both have approximately 68% of the data within one standard deviation of the mean A) I, II, and III B) I and II only C) I and III only D) II and III only 3.

5. A particular tire manufacturer recommends 32 psi of pressure for passenger car tires. He conducts a two-tailed t-test to determine whether or not they are keeping them at this pressure. In a random sample of 30 cars, he found a mean of 33 psi with a standard deviation of 3 psi. Which would be used for this test? A) H 0 : the mean pressure is less than 32 psi B) H 0 : the mean pressure is not 32 psi C) H A : the mean pressure is less than 32 psi D) H A : the mean pressure is not 32 psi 4.

6. A particular tire manufacturer recommends 32 psi of pressure for passenger car tires. He conducts a two-tailed t-test to determine whether or not they are keeping them at this pressure. In a random sample of 30 cars, he found a mean of 33 psi with a standard deviation of 3 psi. Which would be the result at the 5% level of signif.? A) Fail to reject the null due to a high p-value B) Reject the null due to a high p-value C) Fail to reject the null due to a low p-value D) Reject the null due to a low p-value 5.

7. Suppose a machine that makes pegs to be used to hold furniture together is malfunctioning, but the manufacturer doesn’t know it. A quality control test is conducted bimonthly with the null stating that the machine is working properly. The p-value for a recent test was 0.185. What probably happens as a result of this test? A) H 0 is not rejected, resulting in a Type I error B) H 0 is not rejected, resulting in a Type II error C) The test correctly fails to reject H 0 D) The test correctly rejects H 0 6.

8. A t-test should not be used to conduct a hypothesis test for a mean if which of the following is true? A) The sample size was only 20 B) The SD of the population is unknown C) A boxplot of the data showed no outliers D) A histogram of the data was strongly skewed left 7.

9. Which of the following is the correct interpretation of a p-value of 0.003? A)The probability of seeing the observed statistic of something more extreme, if the null hypothesis is true, is 0.003 B) The probability of seeing the observed statistic of something more extreme, if the alternative hypothesis is true, is 0.003 C) The probability that the null is true is 0.003 D) The probability of rejecting the null is 0.003 8.