a normal distribution of data has a mean of 90 and a standard deviation of 18. what is the approximate z…

Explanation:

Step1: Recall z - score formula

The z - score formula is $z=\frac{x-\mu}{\sigma}$, where $x$ is the data point, $\mu$ is the mean, and $\sigma$ is the standard deviation.

Step2: Substitute values

Given $\mu = 90$, $\sigma=18$, and $x = 64$. Then $z=\frac{64 - 90}{18}$.

Step3: Calculate the numerator

$64-90=-26$. So $z=\frac{-26}{18}$.

Step4: Calculate the z - score

$z=\frac{-26}{18}\approx - 1.44\approx - 1.4$.

Answer:

B. -1.4