A 95% confidence interval is figured by finding
A)the Z score for the bottom 5% of the distribution.
B)the Z score for the upper 95% of the distribution.
C)the cutoff points for the lower 2.5% and the upper 2.5% of the distribution.
D)the cutoff points for the lower 5% and the upper 5% of the distribution.

Question

Quizplus · Accepted Answer

A 95% confidence interval includes the middle 95% of the distribution, which leaves 2.5% on either end. To find the cutoff points for these ends, we need to find the Z score that corresponds to the lower 2.5% and the upper 2.5% of the distribution (since the Z distribution is symmetric). These cutoff points can be found using a Z table or calculator.

A 95% Confidence Interval Is Figured by Finding