A randomized comparative experiment studied the eect of diet on blood pressure.

Question

A randomized comparative experiment studied the eect of diet on blood pressure. Researchers divided 54 healthy test subjects at random into two groups. One group received a calcium supplement, and the other group received a placebo. At the beginning of the study, the researchers measured many variables on the subjects. The average seated systolic blood pressure of the 27 members of the placebo group was reported to be ¯ x = 114.9 with a sample standard deviation s = 9.3. (a) Give a 95% condence interval for the mean blood pressure of the population from which the subjects were recruited. (b) The recipe you used in part (a) requires an important assumption about the 27 mean who provided the data. What is this assumption? (c) Using the t-table function for the student distribution provided by Excel, recalculate the 95% condence interval.

Explanation / Answer

alpha / 2 = 0.025    df=26         t=2.056

I: 114.9 +/- 2.056 * 9.3 / srqt(27)

114.9 +/- 3.68

111.22 < miu < 118.58

b)

mean = mean of population

SD = SD population / srqt(n)

c)

please post it in a new question since I dont have the table function in Excel

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