Q3 of 249 Page 31

Given that the two numbers appearing on throwing two dice are different. Find the probability of the event ‘the sum of numbers on the dice is 4’.

Let S be the sample space of throwing two dice and the two numbers are different, then the sample space is


S = {(1, 2), (1, 3), (1, 4), (1, 5), (1, 6)


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


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


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


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


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


n(S) = 30


Let B be the event that the sum if the numbers on the dice is 4, then the sample space becomes


B = {(1, 3), (3, 1)}, n(B) = 2


So the probability of the event ‘the sum of numbers on the dice is 4’ is



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