q: There are 3 teams each with 5 basket players. How many combinations are there if we were to pick 2 players from the 3 teams such that no team was picked twice?
Options:
(A) 50
(B) 23
(C) 75
(D) 28
(E) 45
a: OK... There are altogether three arrangements, which are we can select two members each from team A and B, each from team A and C, and each from team B and C. For each arrangement, there are altogether 25 possibilities (5*5) since each team has 5 players. So there are a total of 75 possibilities (25*3).
The answer is (C).

q: The no. of girls in a class are seven times the no. of boys, which value can neverbe the of total students?
Options:
(A) 4
(B) 5
(C) 8
(D) 10
(E) 12
a: OK... Let the boys are X, then girls are 7X, total = X+7X = 8X
So it should be multiple of 8, 30 is not a multiple of 8.
The answer is (C).

q: A and B can do a work in 5 days, B and C in 15 days and C and A in 25 days. In how many days will the work be completed, if all three of them work together?
Options:
(A) 26/18
(B) 42/15
(C) 48/63
(D) 12/36
(E) 150/23
a:
OK... One day work of A and B = 1/5
One day work of B and C = 1/15
One day work of C and A = 1/25
2(A + B + C) = 1/5+ 1/15 + 1/25
2(A + B + C) = 23/75
(A + B + C) = 23/150
Number of days required = 150/23 days.
The answer is (E).