A can-do of work in 30 days. B can do of the same work in 24 days. They worked together for 20 days. C complete the remaining work in 8 days. Working together A, B and C will complete the same work in:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 12 days.
A can-do of a work in 30 days.
A complete the whole work in 3 × 30 = 90 days.
B can do of the same work in 24 days.
B complete the whole work in 60 days.
Total work = LCM of (60 and 90 ) = 180 units.
Efficiency of A = 180/90 = 2 units/day.
Efficiency of B = 180/60 = 3 units/ day.
Work done by A and B in 20 days = 20 × 5 = 100 units.
Now C joined them then the work was done in 8 days.
Efficiency of C = 80/8 = 10 units.
Combined efficiency of A, B, and C = 10 + 3 + 2 = 15 units/day.
Work done by A, B and C together = 180/15 = 12 days.