SOLUTION: Two fair, normal, six sided dice are used in a game of chance at the bar of the CheeseCake Restaurant. If you roll a combined value of '9' or over, you win $1.05 If you roll a '7

Algebra ->  Probability-and-statistics -> SOLUTION: Two fair, normal, six sided dice are used in a game of chance at the bar of the CheeseCake Restaurant. If you roll a combined value of '9' or over, you win $1.05 If you roll a '7      Log On


   



Question 890015: Two fair, normal, six sided dice are used in a game of chance at the bar of the CheeseCake Restaurant. If you roll a combined value of '9' or over, you win $1.05 If you roll a '7' or '8', you lose $3. If you roll less than a '7', you win $0.60.

What is your expected value if you play the game?

Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
Here are all 36 rolls.

(1,1) (1,2) (1,3) (1,4) (1,5) (1,6)

(2,1) (2,2) (2,3) (2,4) (2,5) (2,6) 

(3,1) (3,2) (3,3) (3,4) (3,5) (3,6) 

(4,1) (4,2) (4,3) (4,4) (4,5) (4,6) 

(5,1) (5,2) (5,3) (5,4) (5,5) (5,6) 

(6,1) (6,2) (6,3) (6,4) (6,5) (6,6)  
 

Here are all the rolls with a combined value of '9' or over:

                              (3,6) 

                        (4,5) (4,6) 

                  (5,4) (5,5) (5,6) 

            (6,3) (6,4) (6,5) (6,6)

There are 10 of them, so the probability of getting a roll
with a combined value of '9' or over is 10%2F36 or 5%2F18

Here are the rolls of '7' or '8':

                              (1,6)

                        (2,5) (2,6) 

                  (3,4) (3,5)  

            (4,3) (4,4)  

      (5,2) (5,3) 

(6,1) (6,2)  

There are 11 of them, so the probability of getting a roll
with a '7' or '8' is 11%2F36.

Here are the rolls less than a '7':

(1,1) (1,2) (1,3) (1,4) (1,5) 

(2,1) (2,2) (2,3) (2,4)  

(3,1) (3,2) (3,3)  

(4,1) (4,2)  

(5,1)  

There are 15 of them, so the probability of getting a roll
less than a '7' is 15%2F36 or 5%2F12.

    Rolls    |  Probability |  Winning  |         Expectation
------------------------------------------------------------------------
 '9' or over |     10/36    |   $1.05   |  (10/36) ×  $1.05 =  $0.29 1/6
 '7' or '8'  |     11/36    |  -$3.00   |  (11/36) × -$3.00 = -$0.91 2/3 
less than '7'|     15/36    |   $0.60   |  (15/36) ×  $0.60 =  $0.25
------------------------------------------------------------------------
Totals       |     36/36=1  |           |                     -$0.37 1/2

The expectation is -37%261%2F2 cents.  That means if you play
the game many times, you will average losing 37%261%2F2 cents per game.  

Edwin