Multiple choice

A can complete a piece of work in 18 days, B in 20 days and C in 30 days, B and C together start the work and are forced to leave after 2 days. The time taken by A alone to complete the remaining work is-

  1. 10 days

  2. 12 days

  3. 15 days

  4. 16 days
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

B and C together do 2 days of work: B's rate = 1/20, C's rate = 1/30, combined = 1/12 per day. In 2 days they complete 2/12 = 1/6 of work. Remaining = 5/6. A's rate = 1/18, so time for 5/6 = (5/6) × 18 = 15 days.

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