Question

if you want to be 99% confident of estimating the population mean to within a sampling error of + or - 4 and the standard deviation is assumed to be 13, what sample size is required?

Answer 1

Solution :

Given that,

standard deviation =s =   =13

Margin of error = E = 4

At 99% confidence level the z is,

= 1 - 99%

= 1 - 0.99 = 0.01

/2 = 0.005

Z/2 = 2.58

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

n = ( 2.58* 13/ 4)2

n =70.308

Sample size = n =70