Suppose that you want to estimate the proportion of Cal Poly students who have a
ID: 2930055 • Letter: S
Question
Suppose that you want to estimate the proportion of Cal Poly students who have at least one class on Friday during the current term. You want to determine how many students need to be sampled in order to estimate this proportion to within plus-or-minus 0.03 with 99 % confidence. Lacking any other information, you start by guessing that this proportion might be close to 0.5.
a. Determine how many students need to be sampled to achieve the desired margin-of-error and confidence level.
Round your answer to the nearest integer.
The sample size must be at least _______
Explanation / Answer
Sample size n = Z2 * P( 1-P) / E2
P is proportion and E is margin of error
n = 2.5762 * ( 0.5 * 0.5) / 0.032
= 1842.98
Sample size n = 1843