Question

A game involves rolling a fair six-sided die. If the number facing upward on the die is a whole number multiple of three, the player wins an amount equal to the number on the die times $20. If the number is not a multiple of three, the player gets nothing. What is the expected value of a player's winnings on each roll?

Answer 1

"whole number multiple of 3" only includes sides 3 and 6

expected value, therefore:

(probability of getting 3 or 6)(amount of money won if they get 3 of 6) + (probability of getting 1,2,4,5)(amount of money won if they get 1,2,4,5)

plug the values into this formula and solve

lmk if you're having trouble or want to check your solution