Question

How large must the sample be in order to be 99% confident that the actual mean number of hours read per week is within 3 hours of the sample mean?

here SD = 1.7

I wanna reffer it for study so provide step wise answer...

Answer 1

Solution:

Given ,

= 1.7 ..Population SD

E = 3 Margin of error

c = 99% = 0.99 ...confidence level

Find sample size required.

c = 0.99

= 1- c = 1- 0.99 = 0.01

  /2 = 0.005

Using Z table ,

= 2.576   

Now, sample size (n) is given by,

=  {(2.576* 1.7)/ 3 }²

=  2.13082140444

= 3 ..(round to the next whole number)

Answer : Required Sample size is n = 3