Question

If your population standard deviation is 66.04, then how many people do you need to sample at a minimum to ensure with 95% confidence that you have a maximal margin of error of 1.32?

Round your answer to the nearest whole number

Answer 1

Solution:

Given ,

= 66.04 ..Population SD

E = 1.32 Margin of error

c = 95% =0.95 ...confidence level

= 1- c = 1- 0.95 = 0.05

  /2 = 0.05 2 = 0.025 and 1- /2 = 0.975

Search the probability 0.975 in the Z table and see corresponding z value

=  1.96

Now, sample size (n) is given by,

= {(1.96* 66.04)/ 1.32 }²

=  9615.64473976

= 9616 ..(round to the next whole number)

Answer : 9616