Probability-twelfth grade-1

Two dice are thrown at a time. Find the probability that the sum of the numbers
on the upper faces of the dice is equal to 7.

Solution: If a die is thrown, there are 6 equally likely and mutually exclusive cases. Since two

dice are thrown, the total number of ways = 6 X 6 = 36. If a sum of 7 is to be obtained from the numbers

appearing on the two upper faces, the numbers in the two dice can be (1,6), (2,5), (3,4), (4,3), (5,2), (6,1),

which are six in number.

Therefore, number of favorable cases = m = 6

Total number of cases = 36

Therefore, the required probability = p = m/n = 6/36 = 1/6