Question

A random sample of 100 measurements is selected from a population with unknown mean and standard deviation of 10.

Calculate width of the 95% CI for the mean.

	a.	1.00
	b.	0.196
	c.	1.96
	d.	3.92

Answer 1

Solution :

Given that,

Population standard deviation = = 100

Sample size = n = 100

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 * (10 / 100)

E = 1.96

= 1.96 * 2 = 3.92

option d) is correct