Question

Help please

This Question: 1 pt 30 of 40 (0 complete) distributed with a mean of 100 and a standrd deviation ons 10% of the populabon wil have an IQ less than OA 81 O B. 119 OC. 96 O D. 75

Answer 1

$X\sim N(\mu =100,\sigma =15)$

Z score for below 10% under standard normal curve is -1.28

by using NORMSINV(0.10) in Excel or z table.

$Z=\frac{x-\mu }{\sigma }$

Substitute here all known values and solve for x

$=>-1.28=\frac{x-100 }{15}$

$=>x=(-1.28*15)+100=80.8\approx 81$

Option A) is correct.