Question

a) The critical value of t for a 90​% confidence interval with df=7. ​

b) The critical value of t for a 98​% confidence interval with df=108.

Answer 1

Solution :

Given that,

a)

Degrees of freedom = df =7

At 90% confidence level the t is ,

= 1 - 90% = 1 - 0.90 = 0.10

/ 2 = 0.10 / 2 = 0.05

t _/2,df = t_0.05,7 = 1.895

critical value = 1.895

b)

Degrees of freedom = df =108

At 98% confidence level the t is ,

= 1 - 98% = 1 - 0.98 = 0.02

/ 2 = 0.02 / 2 = 0.01

t _/2,df = t_0.01,108 = 2.361

critical value = 2.361