Question

A random sample of n = 19 school children yielded the following data on their weight (lbs). sample mean: and sample standard deviation: s = 13. At a confidence level of 88%, calculate the margin of error in the estimate of the mean weight of this population of school children.

Answer 1

Solution:

Given:

Sample size = n= 19

Sample standard deviation = s = 13

Confidence level = 88%

We have to find  the margin of error in the estimate of the mean weight of this population of school children.

Formula:

t_c is t critical value for c = 88%  confidence level

Thus two tail area = 1 - c = 1 - 0.88 = 0.12

df = n - 1 =  19 - 1 = 18

Use following Excel command:

=T.INV.2T(two tail area, df)

=T.INV.2T(0.12, 18)

=1.632

Thus t_c = 1.632

Thus margin of error =