A, B and C can do a piece of work in 6 days, 12 days and 24 days respectively. In what time will they all together do it?
A can do a piece of work in = 6 days
B can do a piece of work in = 12 days
C can do a piece of work in = 24 days
∴ A's 1 day work =16
∴ B's 1 day work =112
∴ C's 1 day work =124
(A+B+C)'s 1 day work =16+112+124
=4+2+124=724
∴ (A + B + C) can do the work in =247 days
=337 days