Question

For parts a and b​, use technology to estimate the following. ​a) The critical value of t for a 99​% confidence interval with df equals = 9 . ​b) The critical value of t for a 90​% confidence interval with df equals = 109

Answer 1

Solution :

a ) Given that,

Degrees of freedom = df = 9

At 99% confidence level the t is ,

= 1 - 99% = 1 - 0.99 = 0.01

/ 2 = 0.01 / 2 = 0.005

t _/2,df = t_0.005,9 = 3.250

The critical value = 3.250

b ) Given that,

Degrees of freedom = df = 109

At 90% confidence level the t is ,

= 1 - 90% = 1 - 0.90 = 0.10

/ 2 = 0.10 / 2 = 0.05

t _/2,df = t_0.05,109 = 1.659

The critical value =1.659