suppose that a randomized comparative experiment studies the effect of diet on blood pressure. researchers divide 54 healthy white maples at random into two groups. one group recieves a calcium supplement, and the other group recieves a placebo. at the beginning of the study, the researchers measure several variables on the subjects. the average seated systolic blood pressure of the 27 members of the placebo group is reported to be x(line on top of x)=114.9, with a standard deviation of s=9.3. Give a 95% confidence intervals or the mean systolic blood pressure of the population from which the subjects were recruited. report your values to one decimal place. 95% confidence interval:_______