Normal Distribution: Basic statistics help needed

[lolphysics3]

Homework Statement

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.

Homework Equations

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

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.

 

[NascentOxygen]

Google is invaluable for revision and worked examples. You'll find all you need in this page: http://www.revisesmart.co.uk/maths/statistics-2/normal-distribution.html

Will also need a standard normal distribution table http://www.mathsisfun.com/data/standard-normal-distribution-table.html

Good luck!

 

[HallsofIvy]

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.

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 ).