In a race with 30 runners where 5 trophies will be given to the top 7 runners (the trophies are distinct: first place, second place, etc), how many ways can this be done?
Options:
(A) 8^8 ways
(B) 8^9 ways
(C) 7^5 ways
(D) 8^7 ways
(E) 8^6 ways

7 people can be prized with 5 distinct prizes in 7^5 ways So the answer is: (C).

Sixteen telegenic contestants with a variety of personality disorders are to be divided into two "tribes" of three members each, tribe A and tribe B, for a competition. How many distinct groupings of two tribes are possible?
Options:
(A) 120
(B) 126
(C) 252
(D) 560
(E) 1260

My ans is 16C3 = 560 So the answer is: (D).

A bullet train 140 m long is running at 60 kmph. In how much time will it pass a platform 210 m long?
Options:
(A) 34 Seconds
(B) 22 Seconds
(C) 21 Seconds
(D) 24 Seconds
(E) 29 Seconds

Distance travelled = 140 + 210m = 350m
Speed = 60 * 5/8 = 50/3m
Time = 350 * 3/50 = 21 Seconds So the answer is: (C).

A Martian bat flies at 60 yards per second from its nest to a dry lake. When it arrives there, it immediately continues at 45 yards per second to a nearby cave. If the distance between the lake and the cave is half the distance between the nest and the lake, what is the average speed, in yards per second, of the bat during the whole flight?
Options:
(A) 36
(B) 40
(C) 42
(D) 54
(E) 65
Distance from nest to lake = d, Speed = 60, Time = d/60
Distance from lake to cave = d/2, Speed = 45, Time = d/90
Average speed = (d + d/2)/(d/60 + d/90) = (3/2)/(1/36) = 54 So the answer is: (D).