00:01
Okay, to find e of y, the expected value of y, or its mean value, there's a formula you have to know, sigma y times f of y, which simply means the number, or the outcome, 2, multiplied by 0 .10 plus 5 times 0 .20 plus 6 times 0 .20.
00:33
0 .30 plus 9 0 .40.
00:42
That you work out on a calculator.
00:47
And we get the answer here of 6 .6.
00:54
That's the first one.
00:58
Now to find the variance, first thing we need to do is to work out e of y y squared, expected value of y squared.
01:07
And that is simply going to be sigma y squared f of y.
01:13
So same as above, but replace the y by y squared...