Question

If n=10, ¯ x (x-bar)=32, and s=10, find the margin of error at a 90% confidence level Give your answer to two decimal places.

Answer 1

solution

Given that,

s =10

n = 10

Degrees of freedom = df = n - 1 =10 - 1 =9

At 90% confidence level the t is ,

= 1 - 90% = 1 - 0.90 = 0.1

/ 2 = 0.1 / 2 = 0.05

t /2,df = t0.05,9 = 1.833 ( using student t table)

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

= 1.833 * (10 / 10)

= 5.80

Margin of error = E =5.80