Question

A teacher wants to compare the mean geology scores of two different classes. she is testing the null hypothesis that there is no difference in the population mean scores of the two classes. the difference of the sample means is 51.4. if the standard deviation of the distribution of the difference of sample means is 16.66, what is the 95% confidence interval for the population mean difference?

between -33.2 and +33.2
between -49.9 and +49.9
between -102.8 and +102.8
between -154.2 and +154.2

Answer 1

it this pre calculus

Answer 2

well as i know these intervals show how much of our data are in them
x is mean and b is standard deviation of the distribution

(x-b,x+b) contains about 68 percent of data
(x-2b,x+2b) contains about 96 percent of data
(x-3b,x+3b) contains about 99 percent of data