Question

8)Suppose the following data show the introductory interest rates on a sample of 5 credit cards: 5.2, 1.1, 2.6, 4.2, 3.4. Calculate the mean interest rate of the sample. (please express your answer using 2 decimal places)

9)In an effort to reduce energy costs, a major university has installed more efficient lights as well as automatic sensors that turn the lights off when no movement is present in a room. Historically, the cost of lighting an average classroom for 1 week has been $265. To determine whether the changes have signficantly reduced costs, the university takes a sample of 50 classrooms. They find that the average cost for 1 week is $247 with a standard deviation of $60. Therefore, the test statistic is 2.12. If the critical value is 1.96, what is your conclusion concerning the null hypothesis?

		Reject the null hypothesis
		Fail to reject the null hypothesis

Answer 1

8)Suppose the following data show the introductory interest rates on a sample of 5 credit cards: 5.2, 1.1, 2.6, 4.2, 3.4. Calculate the mean interest rate of the sample.

Sample Mean( ) is the sum of all the values divided by the number of values.

So  the mean interest rate of the sample is 3.3 credit cards.

9 It is given that

the test statistic is 2.12. And the critical value is 1.96,

Decision rule:

1 ) If | Z | > Z_c then we reject null hypothesis

2 ) If | Z | < Z_c then we fail to reject null hypothesis

Where | Z | is the absolute value of test statistic

and Z_c is the critical value.

Here | Z | = 2.12 > Z_c =1.96 so we reject the null hypothesis