If two fair dice are​ rolled, find the probability that the sum of the dice is 7​, given that the sum is greater than 4.

Answer 1

Prob(4) = 3/36 <---- (1,3),(2,2),(3,1)

Prob(3) = 2/36 <--- (1,2) , (2,1)

Prob(2) = 1/36 <---- (1,1)

Total is 6/36

Prob ( greater than 4) = 1 - Prob( x<=4)

= 1 - 6/36

= 30/36

= 5/6

Prob(7) = (1,6), (2,5), (3,4), (4,3), (5,2),(6,1)

= 6/36

= 1/6

1/6 divided by 5/6 = 1/6 * 6/5 = 1/5 = 20%