Suppose that the Blood Alcohol Content (BAC) of students who drink five beers varies from student to student according to a Normal distribution with mean 0.07 and standard deviation 0.01.
The middle 95% of students who drink five beers have a BAC between
A) 0.06 and 0.08.
B) 0.05 and 0.09.
C) 0.04 and 0.10.
D) 0.03 and 0.11.

Question

Quizplus · Accepted Answer

Since the BAC of students who drink five beers follows a Normal distribution with mean 0.07 and standard deviation 0.01, we know that 95% of the observations lie within 1.96 standard deviations of the mean (using the empirical rule or z-scores).

Therefore, we can calculate the range of BAC values corresponding to the middle 95% of students who drink five beers as follows:

Lower bound = mean - 1.96 * standard deviation
= 0.07 - 1.96 * 0.01
= 0.05

Upper bound = mean + 1.96 * standard deviation
= 0.07 + 1.96 * 0.01
= 0.09

Thus, the middle 95% of students who drink five beers have a BAC between 0.05 and 0.09, and the best choice is (B).

Suppose That the Blood Alcohol Content (BAC) of Students Who