The New York Times published the results of a poll that said

The New York Times published the results of a poll that said 18% of Americans dread Valentine\'s Day. The margin of error was 4% at 95% confidence. Which is the correct confidence interval that the poll found?

.14 < p < .22

.16 < p < .20

.91 < p < .99

.93 < p < .97

Solution

Given margin of error =0.04

p= 0.18

So the lower bound is

p - E= 0.18-0.04 =0.14

So the upper bound is

p + E= 0.18+0.04 = 0.22

Answer: .14 < p < .22