For confidence intervals we have covered zconfidence interva

For confidence intervals, we have covered z-confidence interval and t-confidence interval. In practice, we will use z-confidence interval when we know population standard deviation ó, and use t-confidence interval when we DON’T know the population standard deviation ó. In real life practice, it is unlikely to know any population parameters, so a t-inference is a lot more useful. Find critical t* values from t table for following scenarios.

(1) If you want to find 95% confidence interval with sample size n = 15.

(2) If you want to find 90% confidence interval with sample size n = 200.

(3) If you want to find 99% confidence interval with sample size n = 9.

(4) If you want to find 95% confidence interval with sample size n = 60.

(5) If you want to find 85% confidence interval with sample size n = 16.

(6)If you want to find 90% confidence interval with sample size n = 25

Solution

1)

alpha/2 = 0.025

df = 15-1 = 14

critical t = 2.145

2)

alpha / 2 = 0.05

df = 200-1=199

critilca t = 1.645

3)

alpha / 2 = 0.005

df= 8

critical t = 3.355

4)

alpha/2 = 0.025

df = 59

critical t = 2.000

5)

I can gladly help you but you should post it in a new question

6)

alpha/2 = 0.05

df = 24

critical value = 1.711