The Wall Street Journal reports that 44 of economists suppor

The Wall Street Journal reports that 44% of economists support raising the interest rate. The article states that the poll is based on a random sample of 263 economists across the US, and has a margin of error of 6%. What level of confidence did the WSJ use? ---

a. 90%

b. 98%

c. 95%

d. 99%

Solution

Compute Sample Size ( n ) = n=(Z/E)^2*p*(1-p)
Z a/2 at 0.05 is = 1.96
Samle Proportion = 0.44
ME = 0.06
n = ( 1.96 / 0.06 )^2 * 0.44*0.56
= 262.9362 ~ 263

We use the Confidence level 95%