Sorry to bring this to you so late. I have a math exam and there are a couple of questions that I'm having trouble understanding how to solve. questions like these will show up. Googling my question doesn't help much.

Here is question 1.
At the casino, a game costs $1 to play. If you win, you get $4. If the chance of winning is 10%, how much money should you lose each time you play (what is the expected value)? How much will I lose?

Question 2
Sum the numbers 10 + 20 + 30 + .... + 500
This is familiar to me and I know there is a simple solution, but I can't remember it.