Suppose that a Normal model describes the acidity (pH) of rainwater, and that water tested after last week's storm had a z-score of 1.8. This means that the acidity of that rain …
A) had a pH 1.8 standard deviations higher than that of average rainwater.
B) varied with a standard deviation of 1.8.
C) had a pH 1.8 times that of average rainwater.
D) had a pH 1.8 higher than average rainfall.
E) had a pH of 1.8.

Question

Quizplus · Accepted Answer

A z-score of 1.8 indicates that the acidity of the rainwater was 1.8 standard deviations above the mean, not that its pH was 1.8 units higher or that it varied by a standard deviation of 1.8.

Suppose That a Normal Model Describes the Acidity (PH) of Rainwater