You pay $1 for one of 1000 tickets at a fair. 4 numbers are drawn. The holder of the first number drawn will win $500, the holders of the remaining 3 numbers will each receive $100. What are your expected winnings?

Look at the possible outcomes:

Holder of first number: probability 1/1000, winning $500-$1=$499

Holder of remaining three numbers: probability 3/1000, winnings $100-$1=$99

Holder of remaining 996 numbers: probability 996/1000, loss -$1

The expected winnings are:

(1/1000)($499)+(3/1000)($99)+(996/1000)(-$1) = -$0.20

On average, you lose 20 cents.