Multiple choice

If a piece of work can be done by A in 20 days and by B in 30 days, then the number of days taken by them to do the work together is

  1. 10

  2. 25

  3. 15

  4. 12

  5. 16
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The combined rate of work is (1/20) + (1/30) = (3+2)/60 = 5/60 = 1/12. Therefore, they take 12 days to complete the work together.

AI explanation

Using the combined work formula, their combined one day work is 1/20 + 1/30. Finding a common denominator gives 3/60 + 2/60, which equals 5/60 or 1/12. The reciprocal of 1/12 means they take 12 days to complete the work together.

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