A and B can complete a work in 24 days and 36 days respectively. If they work together for 8 days, how much of the work is left?

Answer: A. 1/3
In 8 days, A and B together complete 8*(1/24 + 1/36) = 8*(5/72) = 5/9 of the work. Therefore, the remaining work is 1 - 5/9 = 4/9.
Posted in:  Time & Work -  Aptitude -  Mathematics