Problema Solution

Suppose you pay $1 to play a game which involves rolling 2 dice. If a sum of 2 and 12 comes up, you win $10. Find the expected value of playing this game.

Answer provided by our tutors

we calculate Expected Value by multiplying each outcome by the probability of that outcome, then adding up the products.


First Outcome: win $(10-1) = $9

First Event: sum of 2 and 12 comes up

P(Fist Event) = 1/36 + 1/36 = 2/36 = 1/18


Second Outcome: lose $1

Second Event: sum of 2 and sum of 12 does not come up

P(Second Event) = 1 - 1/18 = 17/18


Expected Value = 9*(1/18) - 1(17/18) = (9 - 17)/18 = - 8/18 = - 4/9 = - 0.444


The expected value of playing the game is -0.444.


we calculate Expected Value by multiplying each outcome by the probability of that outcome, then adding up the products.


First Outcome: win $(10-1) = $9

First Event: sum of 2 and 12 comes up

P(Fist Event) = 1/36 * 1/36 = 1/36*36


Second Outcome: lose $1

Second Event: sum of 2 and sum of 12 does not come up

P(Second Event) = 1 - 1/(36*36) = (36*36-1)/(36*36)


Expected Value = 9*(1/(36*36)) - 1*(36*36-1)/(36*36)= - 13/18 = - 0.992


The expected value of playing the game is -0.992.