Question

Find the critical value

t/α2

needed to construct a confidence interval of the given level with the given sample size. Round the answers to three decimal places.

(a) For level  

99%

and sample size  

9

(b) For level  

99.5%

and sample size  

14

(c) For level  

80%

and sample size  

29

(d) For level  

90%

and sample size  

11

Answer 1

Solution :

From t-table we find critical values   for different levels and sample size.

For this value we need to calculate degrees of freedom (df) and

From t-table, value corresponding df and is our critical value for one-tail

a) level=99% , sample size =9

b) level= 99.5%, sample size =14

c) level=80%, sample size =29

d) level=90%, sample size = 11

df= n-1= 11-1 = 10