Question: A train which has 390 m long, is running 45 kmph. In what time will it cross a person moving at 9 kmph in same direction ?
Options:
(A) 26 sec
(B) 39 sec
(C) 36 sec
(D) 29 sec
(E) 30 sec
Answer: Time taken to cross a moving person = length of train/ relative speed
Time taken = 390/((45-9) (5/18) = 390/ 36*(5/18) = 390/10 = 39 sec
The answer is (B).

Question: A train 210 m long is running at a speed of 45 km/hr. In what time will it pass a bridge 140 m long?
Options:
(A) 40 sec
(B) 50 sec
(C) 44 sec
(D) 49 sec
(E) 28 sec
Answer: Speed = 45 * 5/18 = 25/2 m/sec
Total distance covered = 210 + 140 = 350 m
Required time = 350 * 2/25 = 28 sec
The answer is (E).

Question: If six persons sit in a row, then the probability that three particular persons are always together is -.
Options:
(A) 1/5
(B) 1/7
(C) 1/9
(D) 1/2
(E) 2/7
Answer: 3!4! Required probability = 3!4!/6! = 1/5
The answer is (A).

Question: The average of 7 consecutive numbers is 33. The highest of these numbers is:
Options:
(A) 28
(B) 30
(C) 33
(D) 36
(E) 28
Answer:
The average of 7 consecutive numbers will be the 4th number which is given to be = 33 5th number = 34, 6th number = 35, 7th number = 36
The answer is (D).