Question

A parent believes that the average height for 14 year old girls differs from that of 14 year old boys. The summary data are listed below where height is in feet: the sample mean of 5.1 and the population standard deviation of 0.2 based on a random sample of size 40 from 14 year old girls. What are the point estimate and the margin of error with 95% confidence level?

Answer 1

Solution :

Given that,

Point estimate = = 5.1

= 0.2

n = 40

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z_/2 = Z_0.025 = 1.96

Margin of error = E = Z_/2* ( /n)

= 1.96 * (0.2 / 40)

= 0.062

Margin of error = E = 0.062