Question

From a phone survey, a researcher determined that the true estimate for the proportion of voter who will elect the mayor is likely to be in the interval (0.39, 0.47)
What is the survey's margin of error?

Enter your answer in the box.

+ [ ]



I need help on how to solve the problem.

Answer 1

The margin of error is half the width of the confidence interval:
$M.o.E.=\frac{0.47-0.39}{2}=0.04$
The margin of error is 0.04 or 4%.