Question

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. What does the z-score imply about the acidity of the rain?

A) It means that the acidity of the rain had a pH 1.8 times that of average rainwater.
B) It means that the acidity of the rain had a pH of 1.8.
C) It means that the acidity of the rain had a pH 1.8 standard deviations higher than that of average rainwater.

Answer 1

A z-score of 1.8 implies that the acidity of the rain had a pH 1.8 standard deviations higher than that of average rainwater.

Step-by-step explanation:

A z-score of 1.8 implies that the acidity of the rain had a pH 1.8 standard deviations higher than that of average rainwater. A z-score represents how many standard deviations above or below the mean a particular value is from a normal distribution. In this case, a positive z-score indicates that the acidity of the rain is higher than average.