# Normal Probabilty Distrubtion

• Mar 9th 2011, 06:30 PM
ChrisFree55
Normal Probabilty Distrubtion
Assume that the salaries of elementary school teachers in the United States are normally distrubted with a mean of 36,000 and a standard deviation of 5000. what is the cutoff salary for teachers in the top 10%

and a second problem:

Assume that the heights of men are normally distributed with a mean of 68..0 inchea and a standard deviation of 3.5 inches. If 100 men are randomly selected, find the probability that they have a mean height greater than 69 inches
• Mar 9th 2011, 06:56 PM
pickslides
Quote:

Originally Posted by ChrisFree55
Assume that the salaries of elementary school teachers in the United States are normally distrubted with a mean of 36,000 and a standard deviation of 5000. what is the cutoff salary for teachers in the top 10%

Here's a thought for the first one.

$\displaystyle \displaystyle P\left(Z<\frac{X-36000}{5000}\right)= 0.9$

solve for $\displaystyle \displaystyle X$