Multiple choice

A can complete 25% of a work in 10 days, B can complete 40% of the same work in 20 days and C can complete 50% of same work in 30 days. They started work together. A and B left the work after 10 days. C completed the remaining work. What is the time taken to do the total work ?

  1. 33 days

  2. 31 days

  3. 30 days

  4. 32 days
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A's rate: 25%/10 days = 2.5% per day. B's rate: 40%/20 days = 2% per day. C's rate: 50%/30 days = 1.67% per day. Work done in first 10 days (A+B+C): 10 × (2.5 + 2 + 1.67) = 10 × 6.17 = 61.7%. Remaining 38.3% done by C alone: 38.3/1.67 ≈ 22.9 days. Total ≈ 32.9 ≈ 33 days. Option A is correct.

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