Question

A certain survey conducted had a population proportion of at most 22% for people who agreed. What is the confidence level if 20% of the people sampled agreed, and the standard error of the proportion is ±1%?

Answer 1

the standard error is defined as \[\sigma/\sqrt n\]
which is part of the confidence interval calculations if memory serves.

Answer 2

given:\[z=\frac{\hat p-p}{\sigma/\sqrt n}\]
the CI is simply:\[\hat p\pm z(\sigma/\sqrt n)\]

Answer 3

the z is determined by the level of significance. usually as 90, 95, or 99%