A random sample of 5 exam scores showed the following: 60, 90, 70, 80, 100.

A random sample of 5 exam scores showed the following: 

60, 90, 70, 80, 100. 

(1) Calculate sample mean

(2) Calculate sample standard deviation

(3) Find 95% confidence interval of the sample mean using the student -t distribution table.

Let m be the population mean of the exam. And we state the following hypothesis:

      H0: μ= 75,       H1: μ≠ 75

(4) Calculate the t-test statistic tcalc .

(5) At α = .05 (5% significant level), is H0 rejected?

Note: A part of t-distribution table