Multiple choice

A can do a piece of work in $8$ days and B can do it in $4$ days. Both of them working together will finish it in

  1. $12$ days
  2. $4$ days
  3. $2$ days
  4. $\displaystyle 2\frac{2}{3}$ days
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A's rate is 1/8, B's rate is 1/4. Combined rate = 1/8 + 2/8 = 3/8. Time taken = 8/3 = 2 and 2/3 days.

AI explanation

Using the combined work formula, the time taken to complete the work together is the product of their individual times divided by their sum. The calculation is 8 multiplied by 4, which is 32, divided by the sum of 8 and 4, which is 12. Dividing 32 by 12 gives 8/3 days, which is equivalent to 2 2/3 days.

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