Question

A political candidate has asked you to conduct a poll to determine what percentage of people support her. If the candidate only wants a 1% margin of error at a 99% confidence level, what size of sample is needed

Answer 1

16589.44

Explanation:

z score for 99% confidence interval = 2.576

Margin of error = 1% = 0.01

Formula =

Margin of error = z score × p(1 - p)/n

0.01=2.576 × √ (0.25)/n

0.01=2.576 × 0.5/√ (n)

Crops Multiply

0.01× √ (n) = 2.576 × 0.5

divide both sides by 0.01

√(n) = 2.576 × 0.5/ 0.01

√n =128.8

Square bother sides

n = 128.8²

n = 16589.44