A first sample of 28 men who were recovering from a heart attack and a second independently selected sample of 30 men who had not had a heart attack was taken with the goal of comparing mean cholesterol levels. The men in the samples were the same age. Researchers were investigating whether the mean cholesterol for the men who were recovering from heart attacks would be higher than the mean level for the other men.

The means and the standard deviations for the two groups are shown below.

Sample

N

Mean

StDev

Sample 1

28

253.9

47.7

Sample 2

30

193.1

22.3

₁ represents the population mean for group 1(individuals recovering from heart attacks)

₂ represents the population mean for group 2(individuals recovering from heart attacks)

a)Give the appropriate null- and alternative hypotheses,

b)Use Minitab to test the hypothesis for the difference in two means.

c)What is the t-value and the p-value?

d)What is the decision regarding the null hypothesis? Use a 5% significance level.

e) What is the conclusion regarding the investigation?