Question

If n=27, ¯ x (x-bar)=47, and s=6, find the margin of error at a 90% confidence level Give your answer to two decimal places.

Answer 1

Given that,

= 47

s =6

n = 27

Degrees of freedom = df = n - 1 =27 - 1 = 26

At 90% confidence level the t is ,

= 1 - 90% = 1 - 0.90 = 0.1

/ 2 = 0.1 / 2 = 0.05

t /2,df = t0.05,26 = 1.706 ( using student t table)

Margin of error = E = t/2,df * (s /n)

= 1.706 * (6 / 27) = 1.97