Answer:
To calculate the sample size required to estimate the percentage of adults over 25-30 who never graduated from high school with a 95% confidence level and a 5% margin of error, 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 associated with the desired confidence level (1.96 for 95% confidence)
- p is the estimated proportion of the population with the characteristic we are interested in (we'll use 0.22, the proportion for adults over 50 who never graduated from high school)
- E is the desired margin of error (0.05)
Plugging in the values, we get:
n = (1.96^2 * 0.22 * (1-0.22)) / 0.05^2
n = 422.5
Rounding up to the nearest whole number, we need a sample size of 423 to estimate the percentage of adults over 25-30 who never graduated from high school with a 95% confidence level and a 5% margin of error.