# Thread: Expected Value of Normal Distribution

1. ## Expected Value of Normal Distribution

Please help with the following:
Just as the difference between 2 sample means is normally distributed for large samples, so is the difference between 2 sample proportions, that is , if Y1 and Y2 are independent binomial variables with parameters (n1, p2) and (n2,p2) respectively, then (Y1/n1) – (Y2/n2) is approximately normally distributed for large quantities of n1 and n2
• Find E(Y1/n1 –Y2/n2)
• Find V(Y1/n1 – Y2/n2)
Thanks in advance

2. Originally Posted by lolu
Please help with the following:
Just as the difference between 2 sample means is normally distributed for large samples, so is the difference between 2 sample proportions, that is , if Y1 and Y2 are independent binomial variables with parameters (n1, p2) and (n2,p2) respectively, then (Y1/n1) – (Y2/n2) is approximately normally distributed for large quantities of n1 and n2
• Find E(Y1/n1 –Y2/n2)
• Find V(Y1/n1 – Y2/n2)
Thanks in advance
Read through this: Mean and Variance of Random Variables

(About halfway down and at the end are formulae relevant to your question).