This is discrete, so it's the sum instead
Now use the geometric sum from calc2, that's why this is a geometric random variable
You can prove directly that the mean is 1/p.
So with p=.2 so the mean is indeed 5.
Can someone help me with this problem? I don't understand how to do it, I know that the mgf is definied as the integral from negative to positive infinity e^(tx)f(x) but I don't understand how to do it for this question
This is discrete, so it's the sum instead
Now use the geometric sum from calc2, that's why this is a geometric random variable
You can prove directly that the mean is 1/p.
So with p=.2 so the mean is indeed 5.