Answer:
Step-by-step explanation:
a) This is a right tailed test. The significance level is α. The critical value corresponding to 1 - α is 3.733. From the t distribution table with a df of 15, 1 - α = 0.999
α = 1 - 0.999 = 0.001
b) This is a left tailed test. Degree of freedom, df = n - 1 = 24 - 1 = 23
The critical value corresponding to 1 - α is - 2.500. From the t distribution table with a df of 23, 1 - α = 0.99
α = 1 - 0.99 = 0.01
c) This is a two tailed test. Degree of freedom, df = n - 1 = 31 - 1 = 30
The critical value corresponding to 1 - α/2 is 1.697. From the t distribution table with a df of 30, 1 - α/2 = 0.95
α/2 = 1 - 0.95 = 0.05
α = 2 × 0.05
α = 0.1