Question

US Weekly magazine claims that 32% of its readers believe Angelina Jolie was best dressed at the Academy awards. To verify this claim, how large a sample is needed for a 0.05 margin of error at a 95% confidence level?

Answer 1

Answer: 335

Explanation:

Formula for sample size :

`n=p(1-p)((z^*)/(E))^2`, where p =population proportion, z* = critical z-value, E = Margin of error.

Given: p = 32% = 0.32

E = 0.05

Critical z-value for 95% confidence = 1.96

Required sample size :

`n=(0.32)(1-0.32)((1.96)/(0.05))^2\\\\=334.372864\approx335`

Hence, the required sample size = 335