Question

A test was given to a group of students. The grades and gender are summarized below: A B C Total Male 9 11 15 35 Female 4 10 14 28 Total 13 21 29 63 Let p represent the percentage of all male students who would receive a grade of B on this test. Use a 85% confidence interval to estimate p to three decimal places. Enter your answer using decimals (not percents).

Answer 1

The data is a s below

	A	B	C	Total
Male	9	11	15	35
Female	4	10	14	28
Total	13	21	29	63

% of all males that would receive a grade of B, i.e (11 / 35) = 0.3143

1 - p = 0.6857

The Z critical at alpha = 0.15 is 1.44

The Confidence Interval is given by ME, where

The Lower Limit = 0.3143 - 0.113 = 0.2013       0.201

The Upper Limit = 0.3143 + 0.113 = 0.4273   0.427

The 85% Confidence Interval is (0.201 < p < 0.427)

_____________________________________________