A can do a piece of work in 4 hours; B and C together can do it in 2 hours, which A and C together can do it in 2 hours. How long will B alone take to do it?
Options:
(A) 2hours
(B) 3hours
(C) 4hours
(D) 5hours
(E) 6hours Stream of consciousness:
A's 1 hour work = 1/4;
(B + C)'s 1 hour work = 1/2;
(A + C)'s 1 hour work = 1/2
(A + B + C)'s 1 hour work = (1/4 + 1/2) = 3/4
B's 1 hour work = (3/4 - 1/2) = 1/4
B alone will take 4 hours to do the work.
Thus, the answer is (C).