Question

You are to estimate the average number of hours that students who are planning to enroll at a college in the fall semester will be taking. You don’t know the standard deviation (or variance), but from previous semesters you have an idea about the range. Historically, the lowest number of hours taken is 1 (usually a PE course). At the other end of the spectrum, the most hours a student has ever been enrolled for is 24. Using industry convention, you want your statistic to be within .5 credit hours of the population parameter with a 95% level of confidence. What is the required size for your simple random sample?

Answer 1

The required sample size (n) is given by:

Given:

= 0.05

From Table, critical values of Z= 1.96

Range = Maximum - Minimum

             = 24 - 1

              = 23

By Range Rule of Thumb :

s = Range/4

   = 23/4

    = 5.75

e = 0.5

Substituting, we get:

So,

Answer is:

509