Multiple choice

Ram, Karan and Vineet take a contract to build a house. Ram can build the house alone in 10 days. Similarly, Karan and Vineet can build the house alone in 20 and 40 days, respectively. They start the work alternately. It means that on the 1st day, only Ram works, on the 2nd day, only Karan works and on the 3rd day, only Vineet works, and so on till the work is finished. Find the total time taken by them to build the house.

  1. 16 days

  2. 15.5 days

  3. 17 days

  4. 16.5 days

  5. 17 1 7 days
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Ram's rate = 1/10, Karan = 1/20, Vineet = 1/40. In 3 days, they do 1/10 + 1/20 + 1/40 = 7/40. In 6 cycles (18 days), they do 42/40 (too much). In 5 cycles (15 days), they do 35/40. Remaining work = 5/40 = 1/8. Day 16: Ram does 1/10. Remaining = 1/8 - 1/10 = 1/40. Day 17: Karan does 1/20. He finishes the 1/40 in half a day. Total = 16.5 days.

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