HELP ME PLEASE!!!

Question

Write an inequality that represents the numbers that are two standard deviations above and below the mean of the data set: 78, 67, 90, 91, 65, 78, 79.

Answer 1

mean = arithmetic average = 548/7= sum of the data divided by the number of data

var = sum of squared differences from the mean divided by 6 is this is a sample

or divide by 7 if it's the entire population

standard deviation = sd = square root of variance

548/7- 2sd < 548/7 < 548/7 +2sd

(548/7-2sd, 548/7+2sd) is the 95% confidence interval