Multiple choice

A is thrice as efficient as B and completes a piece of work in 40 days less than the number of days taken by B. What will be the number of days taken by both of them working together?

  1. 225 days

  2. 15 days

  3. 20 days

  4. 18 days
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let B take x days, then A takes x/3 days. x - x/3 = 40, so 2x/3 = 40, x = 60. A takes 20 days, B takes 60 days. Together they take (20 * 60) / (20 + 60) = 1200 / 80 = 15 days.

AI explanation

Let B take x days, so A takes x/3 days, and the difference x - x/3 = 40 means B takes 60 days and A takes 20 days. Their combined 1-day work is 1/60 + 1/20 = 4/60. They will complete the work together in 60 / 4, which equals 15 days.

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