00:01
For the first problem, finding the expected value of the random variable is as simple as taking the product of the value or each value of x with its respective probability.
00:11
So we'd have 3 times 0 .25 plus 6 times 0 .5 plus 9 times 0 .25.
00:18
So we have that our expected value is equal to 6.
00:22
Then for calculating the variance, we'll also want to find the expected value of x squared.
00:27
So we would want to do 3 squared times 0 .25.
00:33
Or actually, i'll just do it the hard way.
00:35
It will be 9 times 0 .25 plus 36 times 0 .5 plus 81 times 0 .25, which gives us a, one second, here.
00:45
Expective value of x squared as 40 .5.
00:48
And we'd have that the variance is going to be equal to the expected value of x squared, 40 .5, minus the square of the expected value...