Question

A researcher wishes to estimate the mean weight of Americans within 1 pound. What sample size should be chosen to find the mean weight at a 98% confidence level? Suppose we know that the population standard deviation is 3 pounds.

	a.	752
	b.	5
	c.	48
	d.	49

Answer 1

Solution :

Given that,

Population standard deviation = = 3

Margin of error = E = 1

At 98% confidence level the z is,

= 1 - 98%

= 1 - 0.98 = 0.02

/2 = 0.01

Z/2 = Z 0.01 = 2.326

sample size = n = [Z/2* / E] 2

n = [ 2.326 * 3 / 1 ]2

n = 48.69

Sample size = n = 49

Correct option ; - ( d )