Data Answer sheet Round all calculations to at least 4 decim

Solution

if sigma is unkowm we will use T distribution tables

if sigma is know we will use Z distribution table

1) confidence interval

alpha = 0.10 alpha/2 = 0.05

df = 41

critcal values : +/-1.684

2)

alpha = 0.01

df = 43

critical value : -2.423

3)

2 tailed test

alpha / 2= 0.025

df = 8

critical values : +/-2.306

4) confidence interval

alpha / 2 = 0.05

critical values : +/- 1.64

5) lower tailed

alpha = 0.01

critical value -2.32

6) upper tailed

alpha = 0.05

critical value : +1.64