# Homework Help: Expected Value (probability problem)

1. Oct 11, 2009

### snoggerT

Prizes and the chances of winning in a sweepstakes are given in the table below.
Prize: Chances
$25,000,000: 1 chance in 400,000,000$250,000: 1 chance in 150,000,000
$75,000: 1 chance in 50,000,000$10,000: 1 chance in 4,000,000
$800,000: 1 chance in 500,000 A watch valued at$70: 1 chance in 8,000

Find the expected value (in dollars) of the amount won by one entry.

E(X) = X_1*P(X_1)+X_2*P(X_2)+....

3. The attempt at a solution

I used the formula listed above and do not get the right answer. I'm really unsure as to why that doesn't work. I use the dollar values for my X and then the chance as my P(X). Can someone explain to me where my fault is in working this problem?

2. Oct 11, 2009