Q: 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
A: OK... Stream of consciousness: 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).

Q: A train running at the speed of 60 km/hr crosses a pole in 12 sec. What is the length of the train?
Options:
(A) 356
(B) 200
(C) 127
(D) 279
(E) 150
A: OK... Stream of consciousness: Speed = 60 * 5/18 = 50/3 m/sec
Length of the train = speed * time = 50/3 * 12 = 200 m
The answer is (B).

Q: There are different 5 circles. What is the number of the greatest possible points with which the circles intersect?
Options:
(A) 20
(B) 10
(C) 15
(D) 22
(E) 21
A: OK... Stream of consciousness: Maximum points of intersection between n different circles = n*(n - 1) = 5*4 = 20
The answer is (A).

Q: Which one of the following is a prime number?
Options:
(A) 10
(B) 61
(C) 49
(D) 75
(E) 91
A:
OK... Stream of consciousness: 61 is divisible by 1, and itself. So, it is a prime number.
The answer is (B).