Question

What is the margin of error for 95% confidence for a sample of size 250 where p = 0.45?

A. 0.0541
B. 0.0775
C. 0.0706
D. 0.0617

Answer 1

0.0617

Explanation:

so the formula is 1.96
`\sqrt{(p(1-p))/(n) }`

P is the proportion (.45) and n is the sample size (250). Inserting these into the problem, we get 1.96
`\sqrt{(.45(1-.45))/(250) }`. Solving this out, you should solve the inside of the square root to get .00099. Take the square root of this, and multiply by 1.96 to get your answer!

This method applies to any problems with the same basic format. Good luck!