Multiple choice

A and B can do a work together in 18 days. A is three times as efficient as B. In how many days can B alone complete the work?

  1. 54 days

  2. 64 days

  3. 72 days

  4. 60 days
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A is three times as efficient as B, so if B does 1 unit/day, A does 3 units/day. Together they do 4 units/day and finish in 18 days, so total work = 4 × 18 = 72 units. B alone does 1 unit/day, so B needs 72/1 = 72 days to complete the work alone.

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