# Probability Mass Function

• Aug 12th 2013, 06:46 AM
99.95
Probability Mass Function
Hi,

I have a question:

Let X be a random variable with a given PMF of:

x | 0 | 2 | 4 | 5
p(x) |0.15 | 0.30 | 0.30 | 0.25

I need to calculate
P[ 2 < X < 4]
would this simply be 0? The question does not specify whether it is a discrete random variable or a continuous random variable.
In the event it is a continuous random variable, how do I find the answer?

thanks.
• Aug 12th 2013, 07:03 AM
Plato
Re: Probability Mass Function
Quote:

Originally Posted by 99.95
Let X be a random variable with a given PMF of:
x | 0 | 2 | 4 | 5
p(x) |0.15 | 0.30 | 0.30 | 0.25
I need to calculate
P[ 2 < X < 4]
would this simply be 0? The question does not specify whether it is a discrete random variable or a continuous random variable.
In the event it is a continuous random variable, how do I find the answer?

The pmf tells you that it is not a continuous random variable.

If it were then it has a completely different pmf.
• Aug 12th 2013, 07:06 AM
99.95
Re: Probability Mass Function
ah, but of course!
Thanks.