Question

If n=31, ¯ x (x-bar)=33, and s=3, find the margin of error at a 90% confidence level Give your answer to two decimal places.

Answer 1

Solution :

Given that,

Point estimate = sample mean = = 33

sample standard deviation = s = 3

sample size = n = 31

Degrees of freedom = df = n - 1 = 30

At 90% confidence level the t is ,

t _/2,df = t_0.05,24 = 1.697

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

= 1.697 * ( 3/ 31)

= 0.91

The Margin of error is 0.91