Person A can do one-fifth of the work in 3 days, while B's efficiency is half of thet of A. In ow many days A and B working together can do half of te work?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 5
Solution:
The total work done by A is in 15 days.
Efficiency of A = 2 × efficiency of B
Hence the time taken by B to complete the work = 2 × 15 = 30 days.
Let the total work done by A and B be 30 units (LCM of 15 and 30)
Hence efficiency of A = 30/15 = 2 units/day
And efficiency of B = 30/30 = 1 unit/day
So, the time taken by both A and B working together and completing half of the work
⇒ [(30/2) units]/(efficiency of A + B)
⇒ 15/3 = 5 days.
Hence, A and B working together can do half of the work in 5 days.