Suppose that vehicle speeds at an interstate location have a normal distribution with a mean equal to 70 mph and standard deviation equal to 8 mph. What is the z-score for a speed of 64 mph?
A) -6
B) -0.75
C) +0.75
D) +6

Question

Quizplus · Accepted Answer

The z-score is calculated using the formula $z = \frac{(X - \mu)}{\sigma}$, where $X$ is the value in question, $\mu$ is the mean, and $\sigma$ is the standard deviation. For a speed of 64 mph, the z-score is $z = \frac{(64 - 70)}{8} = -\frac{6}{8} = -0.75$.

Suppose That Vehicle Speeds at an Interstate Location Have a Normal