q: A train 360 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) 11 sec
(C) 88 sec
(D) 19 sec
(E) 10 sec
a: OK... Speed = 45 * 5/18 = 25/2 m/sec
Total distance covered = 360 + 140 = 500 m
Required time = 500 * 2/25 = 40 sec
The answer is (A).

q: Which of the following numbers is divisible by each one of 3, 7, 9 and 11 ?
Options:
(A) 2079
(B) 456
(C) 974
(D) 562
(E) 300
a: OK... 639 is not divisible by 7
2079 is divisible by each of 3, 7, 9, 11.
The answer is (A).

q: Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 1 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is?
Options:
(A) 40 gallons
(B) 100 gallons
(C) 120 gallons
(D) 180 gallons
(E) 130 gallons
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... Work done by the waste pipe in 1 minute = 1/15 - (1/20 + 1/24) = - 1/40
Volume of 1/40 part = 1 gallons\
Volume of whole = 1 * 40 = 40 gallons.
The answer is (A).