##### Some Important formula on Random Variable

Hi, I am writing here some important formula which will be very useful when you solve GATE questions. I am not giving you the derivation because derivations are not important for the Gate. If you are interested in derivations please refer  to a book by Mr. Ross Sheldon

1. Discrete random variable:

1. Mean
2. Varience
3. S.D                      =

2. Bionomial Distribution:-

• Mean
• Variance
• S.D.

3.Poisson distribution:-

•
• Variance =
•    //in case if n is very large and p is very small.
• mean= variance
• Variance can't be negative.

terms:

• n= no. of trials
• p= probability of success
• q= probability if failure = 1-p