(23.01) In a randomized comparative experiment on the effect of dietary calcium on blood pressure, researchers divided 58 healthy white males at random into two groups. One group received calcium; the other, a placebo. At the beginning of the study, the researchers measured many variables on the subjects. The paper reporting the study gives x⎯⎯⎯=113.7 and s = 9.1 for the seated systolic blood pressure of the 29 members of the placebo group. Give a 96% confidence interval for the mean blood pressure in the population from which the subjects were recruited is.

And the 96% confidence is given by (110.06; 117.34)

Step-by-step explanation:

Information given

represent the sample mean

population mean (variable of interest)

s=9.1 represent the sample standard deviation

n=29 represent the sample size  

Confidence interval

The confidence interval for the mean is given by the following formula:

  (1)

The degrees of freedom are given by:

The Confidence is 0.96 or 96%, the significance is and , and the critical value would be

Replacing the info we got:

And the 96% confidence is given by (110.06; 117.34)

expression #3 is not equivalent. the others are.