Question

statistics students believe that the average score on the first statistics test is 65. A statistics instructor thinks the average score is higher than 65. he samples ten statistics students and obtains the scores 65;65;70;67;66;63;63;68;72;7. he performs a hypothesis test using a 5% level of significance. the data are from a normal distribution.

A) use these data to compare a 95% confidence interval for u.

B) is there enough evidence to reject the claim?

4. it has been reported that the average credit card debt for college seniors is $3262. the student Senate at a large university feels that their seniors have a debt much less than this, so it conducts a student of 50 randomly selected seniors and finds that the Average debt is $2995, and the population standard deviation is $1100. let's conduct the test based on a type l error of a =0.05.

A) use these data to compute a 95% confidence interval for u.

B) is there enough evidence to reject the claim?

Answer 1

3:

First we need to find the mean and SD of data. Following table shows the calculations:

	X	(X-mean)^2
	65	4
	65	4
	70	9
	67	0
	66	1
	63	16
	63	16
	68	1
	72	25
	71	16
Total	670	92

Sample size: n =10

Sample mean :

Sample standard deviation

A)

B)

Since confidence interval contains 65 so we cannot conclude that the average score is higher than 65.

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4:(a)

B)

Since confidence interval contains $3262 so we cannot conclude that  their seniors have a debt much less than $3262.