Question

The mean age of 25 randomly selected lawyers in southern California was 47.5 with the standard deviation 6.5 years, and the confidence level is 92 %

(a) Which critical value that properly applies in this problem . zα/2 or t α/2

critical value = , to answer this quiestion just Write Z or T

(b) Find the critcal value : , Round to 3 decimal places

(c) Find the margin of error : you need to write the fomula, then input values and answer

Fomula : Margin of error =

Input : Margin of error =

Answer : , round to 2 decimal places

(d) Find the 92 % confidence interval for the mean age of all lawyers in southern California.

CI : , Round to 2 decimal places

Answer 1

Sample size, n= 25

Sample mean, = 47.5

Sample standard deviation, s= 6.5

(a) Critical value, that applies to this problem  

(b)Critical value, t(25-1, 0.08/2)= 1.8280

(c) margin of error , E= = = 2.3764

(d) 92% Confidence interval=

=

= ()

= ( 45.1236 , 49.8764