Normal Probability Distributions

[sharp997]

Assume that adults have IQ scores that are normally distributed with a mean of 100 and a standard deviation of 15.

1) Find P10, which is the IQ score separating the bottom 10% from the top 90%.


All of my many different answers are all wrong. The book says the answer is 80.8. How do they arrive at this answer? Please help...Thanks.

 

[tkhunny]

What methods and tools are at your disposal? Table in a book? Calculator? Maple? Matlab? MathCad?

What answers are you getting and how did you get them?

Please make a habit of showing your work.

 

[galactus]

Find .10 in the body of the z table and find its corresponding z score.

Then, use \(\displaystyle z=\frac{x-{\mu}}{\sigma}\) to solve for x.

 

[tkhunny]

You have x
You have mu
You have sigma
If you cannot do the required substitutions, here, you really need to rethink your course selection.
You did not answer any of my questions.

No one can help you if you provide no information.