To estimate the sample size required for estimating the proportion of college students who are working while going to school with a desired accuracy of 4% at a 90% confidence level, we can use the following formula:
n = (Z^2 * p * (1-p)) / (E^2)
where:
n is the sample size
Z is the Z-score corresponding to the desired confidence level (90% confidence level corresponds to a Z-score of 1.645)
p is the estimated proportion (or expected proportion) of the population
E is the desired margin of error
Given:
Desired accuracy (E): 4% or 0.04
Confidence level (Z-score): 1.645 (corresponding to 90% confidence level)
Estimated proportion (p): 0.40 (or 40%)
Plugging the values into the formula, we get:
n = (1.645^2 * 0.40 * (1-0.40)) / (0.04^2)
n = 0.1239 / 0.0016
n ≈ 77.4375
Rounding up to the nearest whole number, the estimated sample size required to achieve the desired accuracy is 78.
So, a sample size of at least 78 college students would be needed to estimate the proportion of college students who are working while going to school with a margin of error of 4% at a 90% confidence level, assuming an estimated proportion of 40%.