Question

If the mean of a set of data is 24, and 18.40 has a z

-

score of

–

1.40, then the

variance must be:

Answer 1

Solution:

Given, $\mu=24,\bar X=18.40,z=-1.40,\sigma=?$

$z=\dfrac{\bar X-\mu}{\sigma} \\ \Rightarrow-1.40=\dfrac{18.40-24}{\sigma} \\ \Rightarrow \sigma=\dfrac{-5.6}{-1.40}=4$