a sample of 12 observations taken from a normal distribution produced the following data. 13 15 9 11 8 16 4 9 0 14 16 12 . construct the 95% confidence interval for mean

95% interval = mean ± 2 SD

Find the mean first = sum of scores/number of scores

Subtract each of the scores from the mean and square each difference. Find the sum of these squares. Divide that by the number of scores to get variance.

Standard Deviation = square root of variance

I'll let you do the calculations.