VITEEE 2011 Paper

Let A and B be two events such that A= getting number 2 at least once B = getting 7 as the sum of the numbers on two dice Here, A= {(2,1), (2,2), (2,3), (2,4), (2,5), (2,6), (1,2), (3,2), (4,2), (5,2), (6,2)} and B = {(2,5), (5,2), (6,1), (1,6), (3,4), (4,3)} ∴ P (A) = $\frac{11}{36}$ , P (B) = $\frac{6}{36}$ P (A ∩ B) = $\frac{2}{36}$ ∴ Required probability P (A/B) = $\frac{P(A\cap B)}{P(B)}$ = $\frac{\frac{2}{36}}{\frac{6}{36}}$ = $\frac{2}{6}$ = $\frac{1}{2}$