Multiple choice

A can do a piece of work in 20 days and B can do the same work in 15 days.How long will they take to finish the work, if both work together?

  1. $13\dfrac{1}{2}Days$

  2. 10 days
  3. $8\dfrac{4}{7}Days$
  4. $17\dfrac{1}{2}Days$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Combined rate = 1/20 + 1/15 = 3/60 + 4/60 = 7/60. Time = 60/7 = 8 and 4/7 days.

AI explanation

The combined one day work is the sum of their individual one day works: 1 divided by 20 plus 1 divided by 15, which equals 3 divided by 60 plus 4 divided by 60 equals 7 divided by 60. The total time taken is the reciprocal of their combined one day work, calculated as 60 divided by 7. Therefore, they will take 8 and 4 over 7 days to finish the work together.

Keep practicing — related questions