A researcher wants to estimate the proportion of manufacturing companies that use the Six Sigma method. For this purpose, she will take a random sample of 50 manufacturing companies and find out how many of them use this method. She estimates that the proportion will be anywhere from 0.4 to 0.55. Of all these proportions, which one would produce the widest 95% confidence interval for the population proportion?
A) 0.4
B) 0.45
C) 0.5
D) 0.55
E) 0.6

Question

Quizplus · Accepted Answer

The widest confidence interval occurs when the sample proportion is 0.5, as the standard error is maximized at this value.

A Researcher Wants to Estimate the Proportion of Manufacturing Companies