Find the expected value of the random variable.?

In a box of 9 batteries, 7 are dead. You choose two batteries at random from the box.


Let the random variable X be the number of good batteries you get. Find the expected value of X.








A. = 0.44








B. = 0.25








C. = 0.56








D. = 0.88








E. = 1.56

Find the expected value of the random variable.?
P(G) = 2/9


P(B) = 7/9





E(X) = ∑ xp


= 0*(7/9)(7/9) + 1*2*(2/9)(7/9) + 2(2/9)(2/9)


= 28/81 + 8/81


= 36/81


= 0.444
Reply:2