Question

One of the games in a fundraiser involves rolling a six-sided die. The rule is that a player has to donate six times the value shown on the die. What is the expected value of a donation?

A.
$21

B.
$27

C.
$30

D.
$36

Answer 1

expected value (EV) formula above. It's a lot simpler than it looks.

for every outcome, multiply:

(the value of that outcome)(the probability of getting that outcome)

then, once you've calculated this for all outcomes, add the products together.

Answer 2

I'll walk you through part of the problem.

if you roll a 1 on the die, that means you have to donate $6 (since 1 * 6 = 6). the probability of getting 1 on a die is 1/6. so the expected value so far is 6 * (1/6) = 1

if you roll a 2 on the die, that means you have to donate $12 (since 2 * 6 = 12). the probability of getting 2 on a die is 1/6. so the expected value for this outcome is 12*(1/6) = 2

repeat for all 6 outcomes, then add up the results