Question

A random sample of 299 adult Canadians was taken, and 206 of them said that they always vote in federal general elections. Find a 92% confidence interval for the proportion of adult Canadians who say that they always vote in federal general elections.

Answer 1

Sample proportion = 206 / 299 = 0.689

92% confidence interval for p is

- Z/2 * sqrt [ ( 1 - ) / n ] < p < + Z/2 * sqrt [ ( 1 - ) / n ]

0.689 - 1.7507 * sqrt [ 0.689 ( 1 - 0.689) / 299] < p < 0.689 + 1.7507 * sqrt [ 0.689 ( 1 - 0.689) / 299]

0.642 < p < 0.736

92% CI is ( 0.642 , 0.736 )