q: Two trains are traveling on parallel tracks in the same direction. The faster train travels at 130 miles per hour, while the slower train travels at 100 miles per hour. At 2 o'clock the faster train is 25 miles behind the slower one. How far apart are the two trains at 5 o'clock?
Options:
(A) 60 miles
(B) 80 miles
(C) 90 miles
(D) 65 miles
(E) 400 miles
a: OK... Answer = D. 65 miles
Relational speed = 130 - 100 = 30 miles per hour
In 3 hours, difference = 30 * 3 = 90 miles
Fast train trailing 25 miles, so effective difference = 90 - 25 = 65 miles
The answer is (D).

q: What percent is 120 of 90?
Options:
(A) 133 1/3 %
(B) 134 1/3 %
(C) 135 1/3 %
(D) 140 1/3 %
(E) 143 1/3 %
a: OK... 120/90 = 4/3
4/3 100 = 400/3 = 133 1/3 %
The answer is (A).

q: A 600 meter long train crosses a signal post in 40 seconds. How long will it take to cross a 3 kilometer long bridge, at the same speed?
Options:
(A) 4 min
(B) 5 min
(C) 6 min
(D) 8 min
(E) 10 min
a:
OK... S = 600/40 = 15 mps
S = 3600/15 = 240 sec = 4 min
The answer is (A).