11. A is twice as good as workman as B and together they finish a piece of work in 18 days. In how many days will A alone finish the work?
Answer:
(A's 1 day's work) : (B's 1 day's work) = 2:1
(A+B)'s 1 day's work = 1/18.
Therefore A's 1 day's work = [1/18 * 2/3] = 1/27.
Hence, A alone can finish the work in 27 days.
