Multiple choice

A can do 1/3 of a piece of work in 5 days and B can do 2/5 of the work in 10 days. In how many days can both A and B together do the work?

  1. 31 4

  2. 44 5

  3. 75 8

  4. 85 9
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A does 1/3 work in 5 days, so A does full work in 15 days. B does 2/5 work in 10 days, so B does full work in 25 days. Combined rate = 1/15 + 1/25 = (5+3)/75 = 8/75. Time = 75/8 days.

AI explanation

A can do 1/3 of the work in 5 days, so A alone can complete the entire work in 15 days. B can do 2/5 of the work in 10 days, so B alone can complete the entire work in 25 days. Using the formula for working together, (15 * 25) / (15 + 25) = 375 / 40, which simplifies to 75/8 days. The result is 75/8 days.

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