# Normal Distribution: Basic statistics help needed!

1. Apr 16, 2012

### lolphysics3

1. The problem statement, all variables and given/known data

In math 334 one semester, the average student made 1200 computations per month with a standard deviation of 150 computations. Assume that the number of computations is approximated by a normal curve. Find the percent of students making between 1200 and 1600 computations a month.

2. Relevant equations
standard bell curve equation. I don't really know what specific ones I'm supposed to use for a problem like this.

3. The attempt at a solution
I figured that the answer would have to be the prob. of a student making less than 1200* the prob of a student making less than 1600. Which would be 1/2*prob of making less than 1600, which I can't seem to figure out.

2. Apr 16, 2012

### Staff: Mentor

Last edited: Apr 16, 2012
3. Apr 16, 2012

### HallsofIvy

Staff Emeritus
Times? Try subtracting.

If z has the normal distribution with mean $\mu$ and standard deviation $\sigma$ then $(z- \mu)/\sigma$ has the standard normal distribution for which you probably have tables (a good one is at http://www.math.unb.ca/~knight/utility/NormTble.htm [Broken]).

Last edited by a moderator: May 5, 2017