00:01
In this question, we are given the following data between repair calls and the probability.
00:06
For the repair calls value 1, we have probability 0 .2.
00:10
For x is equal to 2, probability is 0 .3.
00:13
For x equals to 3, probability is 0 .3.
00:17
And for x equals to 4, probability is 0 .2.
00:20
Therefore, we have the expected the expected calls per hars is equal to calls per hr is equal to e of x which is equal to summation of x times of p of x so we have 1 times of 0 .2 plus 2 times of 0 .3 plus 3 times of 0 .3 plus 4 times of 0 .2 so on cap.
00:57
Calculating this, we get 0 .2 plus 0 .6 plus 0 .9 plus 0 .8.
01:06
Therefore, the expected calls per heart denoted by e of x is equal to 2 .5.
01:12
This is the value of expected calls per hour.
01:15
Now next, calculating the standard deviation, calculating standard deviation, which is equal to square root of variance, positive square root of variance.
01:28
So we know variance is calculated as e of x minus e of x squared minus e of x whole square...