Question

9. A null hypothesis makes a claim about a _______.

Multiple Choice

• sample statistic

• population parameter

• sample mean

• type II error

10. The average cost of tuition plus room and board for a small private liberal arts college is reported to be $8,500 per term, but a financial administrator believes that the average cost is higher. A study conducted using 350 small liberal arts colleges showed that the average cost per term is $8,745. The population standard deviation is $1,200. Let α = 0.05. What is the p-value for this test?

Multiple Choice

• 0.0500

• 0.4938

• 0.0000

• 0.0124

11. The mean annual income of certified welders is normally distributed with a mean of $50,000 and a population standard deviation of $2,000. The ship building association wishes to find out whether their welders earn more or less than $50,000 annually. The alternate hypothesis is that the mean is not $50,000. If the level of significance is 0.10, what is the decision rule?

Multiple Choice

• Do not reject the null hypothesis if computed z lies between −1.960 and +1.960; otherwise, reject it.

• Do not reject the null hypothesis if computed z lies between −1.645 and +1.645; otherwise, reject it.

• Do not reject the null hypothesis if computed z is greater than 1.645; otherwise, reject it.

• Reject the null hypothesis if computed z is below −1.960; otherwise, reject it.

12. A manufacturer wants to increase the shelf life of a line of cake mixes. Past records indicate that the average shelf life of the mix is 216 days. After a revised mix has been developed, a sample of nine boxes of cake mix gave these shelf lives (in days): 215, 217, 218, 219, 216, 217, 217, 218, and 218. Using α = 0.025, has the shelf life of the cake mix increased?

Multiple Choice

• Yes, because computed t is greater than the critical value.

• No, because 217.24 is quite close to 216.

• Yes, because computed t is less than the critical value.

• No, because computed t lies in the region of acceptance.

13. Define the level of significance.

Multiple Choice

• It is the probability of a Type I error.

• It is the beta error.

• It is a z-value of 1.96.

• It is the probability of a Type II error.

14. For a two-tailed test with a 0.05 significance level, where is the rejection region when n is large and the population standard deviation is known?

Multiple Choice

• Greater than +1.960 and less than −1.960

• Greater than +1.645 and less than −1.645

• Between ±1.645

• Between ±1.960

15. Consider a two-tailed test with a level of confidence of 80.30%. The z-value is _______.

Multiple Choice

• 0.85

• 1.96

• 2.58

• 1.29

Answer 1

Solution:

9. A null hypothesis makes a claim about a _______.

Answer: population parameter

Explanation: The null hypothesis is set up to make inference about the population, therefore, a null hypothesis makes a claim about a population parameter

10. The average cost of tuition plus room and board for a small private liberal arts college is reported to be $8,500 per term, but a financial administrator believes that the average cost is higher. A study conducted using 350 small liberal arts colleges showed that the average cost per term is $8,745. The population standard deviation is $1,200. Let α = 0.05. What is the p-value for this test?

Answer: 0.0000

Explanation:

11. The mean annual income of certified welders is normally distributed with a mean of $50,000 and a population standard deviation of $2,000. The shipbuilding association wishes to find out whether their welders earn more or less than $50,000 annually. The alternate hypothesis is that the mean is not $50,000. If the level of significance is 0.10, what is the decision rule?

Answer: Do not reject the null hypothesis if computed z lies between −1.645 and +1.645; otherwise, reject it.

12. A manufacturer wants to increase the shelf life of a line of cake mixes. Past records indicate that the average shelf life of the mix is 216 days. After a revised mix has been developed, a sample of nine boxes of cake mix gave these shelf lives (in days): 215, 217, 218, 219, 216, 217, 217, 218, and 218. Using α = 0.025, has the shelf life of the cake mix increased?

Answer: Yes, because computed t is greater than the critical value.

13. Define the level of significance.

Answer: It is the probability of a Type I error.

14. For a two-tailed test with a 0.05 significance level, where is the rejection region when n is large and the population standard deviation is known?

Answer: Greater than +1.960 and less than −1.960

15. Consider a two-tailed test with a level of confidence of 80.30%. The z-value is _______.

Answer: 1.29