A is three times more efficient as a worker then B, which allows A to complete a job in 60 days less than B. If they work together, they can finish the job in:
Show answer & explanation
Correct answer: B
Explanation
Let B's time = x days
Since A is 3 times as efficient as B, A takes 1/3rd the time B takes.
So A's time = x/3 days
Given: B's time − A's time = 60 days
x − x/3 = 60
2x/3 = 60
x = 90 days (B's time)
A's time = 90/3 = 30 days
Working together:
Combined 1-day work = 1/30 + 1/90 = 3/90 + 1/90 = 4/90 = 2/45
Time taken together = 45/2 = 22.5 days