CAT Exam Numerical Ability Permutation and Combination

In a chess competition involving some boys and girls of a school, every student had to play exactly one game with every other student. It was found that in 45 games both the players were girls, and in 190 games both were boys. The number of games in which one player was a boy and the other was a girl is
(1) 200
(2) 216
(3) 235
(4) 256

Read Solution (Total 2)

Games played among 2 girls out of g girls= 45
» gC2=45 »g(g-1)/2=45 » g(g-1)=90
»»g=10

Games played among 2boys out of b boys= bC2=190
»b(b-1)/2=190 »b=20

Games played involving one girl and one boy= gC1*bC1 =g*b = 10*20=200
9 years agoHelpfull: Yes(4) No(0)

40+190=235 GAMES
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CAT Other Question

Q. There are a certain number of apples in a big box. A boy takes half apple more, than half of them. A second boy takes half apple more than half of the remaining and so on. After the 7th boy takes his share, the number of apples in the box is 635 less than the original number of apples. If no apple is cut in the entire process, how many apples are left after the fifth boy takes apples from the box?

Option
(1) 9
(2) 19
(3) 39
(4) 59 Consider a triangle drawn on the X-Y plane with its three vertices at (41, 0), (0, 41) and (0, 0), each vertex being represented by its (X, Y) coordinates. The number of points with integer coordinates inside the triangle (excluding all the points on the boundary) is
(1) 780
(2) 800
(3) 820
(4) 741