P can finish a work in 18 days. When he had worked for 5 days, Q joined him. If both of them together completed the remaining work in days, then in how many days can Q alone finish 66 % of the same work?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 3.
P finished the work in 18 days.
Let the efficiency of P is 1 unit/day.
Total work = 18 × 1 = 18 units.
P work for 5 days,
Remaining work = 18 - 5 = 13 units.
(P + Q) complete the remaining work in 13/5 days.
The combined efficiency of (P + Q) = 13/(13/5) = 5 units.
Efficiency of Q = 5 - 1 = 4 units/day.
66 % of work = 2/3 × 18 = 12 units.
Time taken by Q to complete 12 units of work = 12/4 = 3 days.