An advertising firm wants to confirm estimates that 18% of households will buy something on the internet next year.What sample size will produce a margin of error of 7% with 90% confidence level?

Question

Quizplus · Accepted Answer

To find the sample size, use the formula for margin of error: ME = Z * sqrt[(p(1-p))/n]. For a 90% confidence level, Z is approximately 1.645. Plugging in the values: 0.07 = 1.645 * sqrt[(0.18(0.82))/n]. Solving for n gives approximately 82.

An Advertising Firm Wants to Confirm Estimates That 18% of Households