A frequency distribution has a mean of 200 and a standard deviation of 20. The class limits for one class are 220 up to 240. What are the standard normal z-statistics for the class limits?
A)−20 and 20
B)−2.0 and −1.0
C)200 and 220
D)1.0 and 2.0

Question

Quizplus · Accepted Answer

The z-statistic is calculated using the formula $z = \frac{(X - \mu)}{\sigma}$, where $X$ is the value, $\mu$ is the mean, and $\sigma$ is the standard deviation. For the lower limit (220), $z = \frac{(220 - 200)}{20} = 1.0$. For the upper limit (240), $z = \frac{(240 - 200)}{20} = 2.0$.

A Frequency Distribution Has a Mean of 200 and a Standard