Question

A sample size of n=100 is drawn from a population whose standard deviation is =3.8 Find the margin of error for a 95% confidence level.

Answer 1

Solution:

Sample size = n = 100

Population Standard deviation =

Confidence level = c= 95%

Margin of Error is given by:

We need to find z_c value for c=95% confidence level.

Find Area = ( 1 + c ) / 2 = ( 1 + 0.95) /2 = 1.95 / 2 = 0.9750

Look in z table for Area = 0.9750 or its closest area and find z value.

Area = 0.9750 corresponds to 1.9 and 0.06 , thus z critical value = 1.96

That is : z_c = 1.96

thus

_{(Round final answer to specified number of decimal places)}