Multiple choice

A, B and C can do a piece of work in 20, 30 and 60 days respectively. How many days does it require to complete the work if A does the work and he is assisted by B and C on every third day? A, B और C क्रमशः 20, 30 और 60 दिनों में एक काम को कर सकते हैं। काम को पूरा करने के लिए कितने दिन की आवश्यकता है यदि A कार्य करता है और उसे हर तीसरे दिन B और C द्वारा सहायता दी जाती है?

  1. 10

  2. 14

  3. 15

  4. 9
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A's efficiency = 1/20, B's = 1/30, C's = 1/60. In 3-day cycle: Day 1: A does 1/20, Day 2: A does 1/20, Day 3: A+B+C do 1/20+1/30+1/60 = 6/60. Total in 3 days = 8/60. In 15 days (5 cycles): 5 × 8/60 = 40/60 = 2/3. On day 15: A works, adding 1/20. Cumulative: 2/3 + 1/20 = 47/60. Work completed.

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