What is the average rate of change between 70, 120 and 90,200

Asimple random sample of size nequals14 is drawn from a population that is normally distributed. the sample mean is found to be x overbar equals 70 and the sample standard deviation is found to be sequals13. construct a 90% confidence interval about the population mean

(hurry! ) which expression is equivalent to the following complex fraction?

Can anyone me with 32,33,36,37,and 40.