Question

Two unbiased dice are thrown. Find the probability that the sum of the numbers appearing is 8 or greater, if 4 appears on the first die. Select the correct answer from above options

Answer 1

Correct Answer - `1/2` Let A = event of getting the sum 8 or greater, and B = event of getting a 4 on the first die. `:. A={(2, 6), (3, 5), (3, 6), (4, 4), (4, 5), (4, 6), (5, 3), (5, 4), (5, 5), (5, 6), (6, 2), (6, 3), (6, 4), (6, 5), (6, 6)}` `B={(4, 1), (4, 2), (4, 3), (4, 4), (4, 5), (4, 6)}`. `(A nn B)={(4, 4), (4, 5), (4, 6)}`. `(A nn B)={(4, 4),(4, 5), (4, 6)}`. `:. n(A)=15, n(B)=6` and `n(A nn B)=3`. Hence, the required probability `=P(A//B)=(n(A nn B))/(n(B))=3/6=1/2`.