Multiple choice

A and B can complete a work in 20 days whereas A and C can complete the same work in 30 days. C alone can complete the work in 40 days. A, B and C work together for 8 days. C alone will complete the remaining work in?

  1. 12 days

  2. 10 days

  3. 16 days

  4. 24 days

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let total work = 120 units (LCM of 20, 30, 40). A+B rate = 6/day, A+C rate = 4/day, C rate = 3/day. So A's rate = 3/day, B's rate = 3/day. All three together: 3+3+3 = 9/day. In 8 days, they complete 72 units. Remaining = 48 units. C alone at 3/day needs 16 days. The key is finding individual rates from combined rates.

Keep practicing — related questions