20 If 2 dice are rolled find the probability of the followin

20. If 2 dice are rolled, find the probability of the following events (a) The sum of the number of dots showing is greater than 8;

Solution

If two dice are rolled then the sum of dots showing greater than 8 will be

(3,6),(4,5),(4,6),(5,4),(5,5),(5,6),(6,3),(6,4),(6,5),(6,6) = 10

Total = 36

P(the sum of number of dots showing greater than 8) = 10/36

(b) There is only one case for two dice to show 2 as a sum which is (1,1), Hence

P(the sum of the dots is 2) = 1/36