The width of the confidence interval for a single proportion

The width of the confidence interval for a single proportion gets narrower (or smaller) when:

a. Neither of the other anser

b.the sample size increases

c.the confidence level percentage gets smaller

d. both of the other answers

Solution

The most practical way to decrease the margin of error is to increase the sample size. Usually, the more observations that you have, the narrower the interval around the sample statistic is. Thus, you can often collect more data to obtain a more precise estimate of a population parameter. i,e, option (b)

The advantage of a lower confidence level is that you get a narrower, more precise confidence interval. i.e. option (c).

Hence Option (d) i.e. both the answers.