The ratio of the efficiencies of A, B, and C is 3 : 5 : 1. Working together, they can complete a piece of work in 5 days. A and B work together work for 3 days. The remaining work will be completed by C alone in how many days?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e. 21 days
Let the efficiencies of A, B, & C be respectively 3, 5 & 1 units
Work done by 3 of them together of day 1 = 3 + 5 + 1 = 9 units
⇒ Total work = 9 × 5
⇒ 45 units
The amount of work completed when A and B work for 3 days = 3(3 + 5)
⇒ 3 × 8 = 24 units
Remaining work = 45 - 24 = 21 units
The number of days taken by C = 21/1
⇒ 21 days