Find the 99% confidence interval for the difference between two means based on this information about two samples. Assume independent samples from normal populations. (Use conservative degrees of freedom.) (Give your answers correct to two decimal places.)

Question

Sample Number Mean Std. Dev.
1 23 38 30
2 11 23 35

Lower Limit:
Upper Limit:

Answer 1

(38-23) -+ 3.169* sqrt((30^2/23 +35^2/11)

Lower limit -23.88

Upper limit 53.88

Answer 2

Thanks for your help!

Answer 3

How did you find the 3.169, please?