Carmela randomly selected 65 stamps from a stamp collection. Eleven of these were commemorative stamps. What is the interval estimate for the proportion of commemorative stamps in the entire collection if the sampling method had a margin of error of ±0.025?

Since there is no mean, we need to first get the probability:

p = 11 / 65 = 0.1692

This will make it easier to compute for the interval estimate. Interval Estimate = probability ± margin of error

upper limit = 0.1692 + 0.025 = 0.1942

lower limit = 0.1692 - 0.025 = 0.1442

So the interval estimate is 0.1442 < x < 0.1942