1. A study is conducted to estimate the difference between the body mass index (BMI) of males and females. The following random samples were obtained with the following results:

Male BMI n = 40 mean = 28.44 standard deviation = 7.39 Female BMI n = 36 mean = 26.60 standard deviation = 5.36

a) Constructa90% confidence interval for the difference in means between male and female BMI measurements.

b) Based only on the confidence interval above, does there appear to be a difference between the average male and female BMI? Justify your answer.

2. In your own words and one complete sentence, briefly state what purpose a confidence interval serves.

3. A random sample of 101 healthy adults had a mean of 98.20F with a standard deviation of 0.62F. Construct a 95% confidence interval for the mean body temperature of a healthy adult.

4. Twelve percent of 900 randomly selected women over the age of forty report using hair coloring.

a) Compute and interpret a 99% confidence interval for the proportion of women over the age of forty who use hair coloring.In your own words and complete sentences, briefly state what purpose a confidence interval serves.

b) A new random sample is needed so that the 99% confidence interval for the percentage of women who report using hair coloring only has a margin of error of 2.5%. How many women over forty would have to be selected? (You can consider the above sample to be a reliable estimate for P)