Average of the first 'n' natural numbers = (n + 1)/2
We get (19 + 1)/2 = 10
Find the average of the first 19 natural numbers?
Options:
(A) 8
(B) 9
(C) 10
(D) 11
(E) 12
(C)

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).
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
(C)

Speed = 90*(5/18) m/sec = 75/3 m/sec
Length of Train (Distance) = Speed * Time
(75/3) * 12 = 300 meter
A train running at the speed of 90 km/hr crosses a pole in 12 seconds. Find the length of the train?
Options:
(A) 150
(B) 872
(C) 287
(D) 288
(E) 300
(E)