Multiple choice

Chainu can complete the work in 30 days. Pinky can complete half of the work in 20 days. Chainu started the work and left the work after 10 days, then Pinky worked for 8 days and left. Rest of the work was done by Disha in 21 days. Disha can complete the whole work in

  1. 32 days

  2. 40 days

  3. 35 days

  4. 45 days

  5. 50 days
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Chainu rate = 1/30. Pinky rate = 1/40 (half in 20 days). Work done: Chainu (10/30) + Pinky (8/40) = 1/3 + 1/5 = 8/15. Remaining work = 7/15. Disha does 7/15 in 21 days, so Disha rate = (7/15) / 21 = 1/45. Disha takes 45 days.

AI explanation

Chainu's 1 day work is 1/30 and Pinky's 1 day work is 1/40 since she does half the work in 20 days. Chainu's 10 day work is 10/30, Pinky's 8 day work is 8/40, so the work finished before Disha joins is 10/30 + 8/40 = 7/12. The remaining work is 1 - 7/12 = 5/12, which Disha does in 21 days, so Disha's 1 day work is (5/12) / 21 = 5/252. Using the basic Time and Work formula, Disha alone will complete the whole work in the reciprocal of her daily work, 252/5 = 45 days.

Keep practicing — related questions