Question

IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. If a certain statistician has an IQ of 140, what percent of the population has a lower IQ?

A. 7%
B. 99.6%
C. 93%
D. 47%
E. 22%

Answer 1

c

Answer 2

wait no thats wrong

Answer 3

then what is it? i have no clue how to do it

Answer 4

Important thing is HOW to get it.

Answer 5

i think its b

Answer 6

yeah how do you get it

Answer 7

i dont know i google it.

Answer 8

Calculate the Z-value by
X=140, mean=\(\mu\)=100, std dev=\(\sigma\)=15
\(Z=(X-\mu)/\sigma=2.667\)
Look up the normal distribution table for the left-tail probability for Z=2.667.
If you textbook does not have a table, use:
https://www.stat.tamu.edu/~lzhou/stat302/standardnormaltable.pdf

Answer 9

what was the answer?