Question

it is known that the population variance equals 529. With a .98 confidence coefficient the sample size that needs to be taken estimate the population mean if the desired margin of error is 3 or less

Answer 1

Solution:

Given ,

Variance ² = 529

So ,

Standard Deviation = 529 = 23

c = 0.98

E = 3

Now ,

= 1 - c = 1 - 0.98 = 0.02

/2 = 0.02/2 = 0.01

Using z table ,

=  2.326

Now, sample size (n) is given by,

=  {(2.326 * 23 )/ 3 }²

=  318.004000444

= 319 ..(round to the next whole number)

Answer : Sample size needed is 319