# Multiplying random value by variance + motivation

1. Apr 8, 2009

### JamesGoh

Just a quick question.

If you want any value to follow a particular probability distribution function (pdf), do you have to multiply that value by the variance of the desired pdf ?

2. Apr 8, 2009

### mathman

What is the probability distribution of the given random variable? If it starts out as standard normal, you can multiply it by the standard deviation (square root of variance) to get a normally distributed r.v. with the desired variance. In general by multiplying by the s.d. you will get a r.v. with the same kind of distribution.

3. Apr 8, 2009

### JamesGoh

thanks for that

Initially, I was concerned with a value following any pdf distribution being multiplied by a specific pdf variance