q: Two trains are moving at 50 kmph and 70 kmph in opposite directions. Their lengths are 170 m and 100 m respectively. The time they will take to pass each other completely is?
Options:
(A) 3 sec
(B) 8 sec
(C) 9 sec
(D) 5 sec
(E) 7 sec
a: OK... 70 + 50 = 120 * 5/18 = 100/3 mps
D = 170 + 100 = 270 m
T = 270 * 3/100 = 8 sec
The answer is (B).

q: A train 460 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
(B) 87
(C) 48
(D) 21
(E) 14
a: OK... Speed = 45 * 5/18 = 25/2 m/sec
Total distance covered = 460 + 140 = 600 m
Required time = 600 * 2/25 = 48 se
The answer is (C).

q: Find the smallest number which should be multiplied with 13225 to make it a perfect square.
Options:
(A) 25
(B) 5
(C) 1
(D) 23
(E) 6
a:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
OK... 13225 = 5*5*23*23
Required smallest number = 1
1 is the smallest number which should be multiplied with 13225 to make it a perfect square.
The answer is (C).