Rs. 5000 is divided into three parts A, B and C. How much A is more than C if their ratio is 1/5:1/5:1/10?
Options:
(A) 1000
(B) 992
(C) 772
(D) 552
(E) 312
Answer and stream of consciousness: (A)
Stream of consciousness: 1/5:1/5:1/10 = 2:2:1
1/5*5000 = 1000
2000-1000 = 1000

A can do a piece of work in 4 hours; B and C together can do it in 3 hours, which A and C together can do it in 2 hours. How long will B alone take to do it?
Options:
(A) 15 hours
(B) 14 hours
(C) 12 hours
(D) 74 hours
(E) 79 hours
Answer and stream of consciousness: (C)
Stream of consciousness: A's 1 hour work = 1/4;
(B + C)'s 1 hour work = 1/3;
(A + C)'s 1 hour work = 1/2
(A + B + C)'s 1 hour work = (1/4 + 1/3) = 7/12
B's 1 hour work = (7/12 + 1/2) = 1/12
B alone will take 12 hours to do the work.

If the ratio of boys to girls in a class is B and the ratio of girls to boys is G; then 10 (B + G) is ?
Options:
(A) Equal to 3
(B) Less than 3
(C) More than 3
(D) Less than 1/3
(E) none of these
Answer and stream of consciousness: (E)
Stream of consciousness: Let number of boys = x
Let number of girls = y
Therefore x/y = B and y/x = G
10(B + G) = 10[(x/y) + (y/x)] = 10[(x2 + y2)/xy] > 10

A 200 meter long train crosses a man standing on the platform in 9 sec. What is the speed of the train?
Options:
(A) 228
(B) 108
(C) 1266
(D) 188
(E) 80
Answer and stream of consciousness:
(E)
Stream of consciousness: S = 200/9 * 18/5 = 80 kmph