A recent poll of 700 people who work indoors found that 278 of them smoke. If the researchers want to be 98% confident of their results to within 3.5%, how large a sample is necessary?
A) 751
B) 1062
C) 1301
D) 532

Question

Quizplus · Accepted Answer

The sample size needed to be 98% confident of the results to within 3.5% is 1062. This is calculated using the formula n = (Z^2 * p * q) / e^2, where Z is the z-score for the desired confidence level, p is the proportion of the population that smokes, q is the proportion of the population that does not smoke, and e is the margin of error. In this case, Z = 2.326, p = 278/700 = 0.397, q = 1 - p = 0.603, and e = 0.035. Plugging these values into the formula gives n = (2.326^2 * 0.397 * 0.603) / 0.035^2 = 1062.

A Recent Poll of 700 People Who Work Indoors Found