Question

A study of 902 decisions (to grant parole or not) made by the Nebraska Board of Parole produced the following 95% confidence interval:

(56.1%, 62.5%)

What is the margin of error?

A) 1%
B) 6.4%
C) 59.3%
D) 3.2%

Is the answer C?

Answer 1

The mean is this:
(56.1% + 62.5%)/2 = 59.3%

Therefore, the margin of error is D.

CI95 = 59.3% ± 3.2%
59.3% - 3.2% = 56.1%
59.3% + 3.2% = 62.5%

Interval is 56.1% to 62.5%