Multiple choice

$A$ can do a piece of work in $20$ days and $B$ in $15$ days .They worked together on it for $6$ days and then, $A$ left . In how many days will $B$ finish the remaining work ?

  1. $ 2\dfrac{5}{2} $
  2. $ 3\dfrac{7}{3} $
  3. $ 2\dfrac{6}{5} $
  4. $ 4\dfrac{1}{2} $
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A's rate = 1/20, B's rate = 1/15. Together they work for 6 days: 6 * (1/20 + 1/15) = 6 * (3/60 + 4/60) = 6 * 7/60 = 7/10. Remaining work = 3/10. B finishes this in (3/10) / (1/15) = 3/10 * 15 = 4.5 days, which is 4 1/2 days.

AI explanation

A's 1 day work is 1/20 and B's 1 day work is 1/15. (A+B)'s 1 day work is (1/20 + 1/15) = 7/60. Their 6 days work is 6 * (7/60) = 7/10. Remaining work is (1 - 7/10) = 3/10. B will finish the remaining work in (3/10) / (1/15) = 4 1/2 days.

Keep practicing — related questions