Question

In a study of speed​ dating, male subjects were asked to rate the attractiveness of their female​ dates, and a sample of the results is listed below ​(1equalsnot ​attractive; 10equalsextremely ​attractive). Construct a confidence interval using a 90​% confidence level. What do the results tell about the mean attractiveness ratings of the population of all adult​ females? 5​, 9​, 3​, 8​, 5​, 4​, 7​, 7​, 9​, 10​, 6​, 9 What is the confidence interval for the population mean mu​? less thanmuless than ​(Round to one decimal place as​ needed.)

A clinical trial was conducted to test the effectiveness of a drug for treating insomnia in older subjects. Before​ treatment,

1414

subjects had a mean wake time of

100.0100.0

min. After​ treatment, the

1414

subjects had a mean wake time of

78.578.5

min and a standard deviation of

22.722.7

min. Assume that the

1414

sample values appear to be from a normally distributed population and construct a

9595​%

confidence interval estimate of the mean wake time for a population with drug treatments. What does the result suggest about the mean wake time of

100.0100.0

min before the​ treatment? Does the drug appear to be​ effective?

Construct the

9595​%

confidence interval estimate of the mean wake time for a population with the treatment.

minless than<muμless than<

min

​(Round to one decimal place as​ needed.)

Answer 1

5	-1.83	3.3489
9	2.17	4.7089
3	-3.83	14.6689
8	1.17	1.3689
5	-1.83	3.3489
4	-2.83	8.0089
7	0.17	0.0289
7	0.17	0.0289
9	2.17	4.7089
10	3.17	10.0489
6	-0.83	0.6889
9	2.17	4.7089

Refer t-table or use excel function "=T.INV.2T(0.10,11)" to find the critical value of t.

The results tell nothing about the population of all adult females, because participants in speed dating are not a representative sample of the population of all adult females.

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Refer t-table or use excel function "=T.INV.2T(0.05,13)" to find the value of t.

The confidence interval the mean wake time of 100.0 min before the treatment, so the means before and after the treatment this result suggests that the drug treatment a significant effect.