SOLUTION: Struggling with expectation, can you help? The number of failures of a computer system in a week of operation has the following pmf: No of failures 0 1 2 3 4 5 6 Pro

Algebra ->  Probability-and-statistics -> SOLUTION: Struggling with expectation, can you help? The number of failures of a computer system in a week of operation has the following pmf: No of failures 0 1 2 3 4 5 6 Pro      Log On


   

Question 316278: Struggling with expectation, can you help?
The number of failures of a computer system in a week of operation has the following pmf:

No of failures
0
1
2
3
4
5
6
Probability
0.18
0.28
0.25
0.18
0.06
0.04
0.01

(a) Find the expected number of failures in a week.
(b) Find the variance of the number of failures in a week.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!

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VAR=%28sigma%29%5E2=sum%28%28x-mu%29%5E2%2AP%28x%29%2C1%2C7%29=1.9076
where
mu is the average x value.