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A can do piece of work in 80 days. He work at it for 10 days and them B alone finishes the remaining work in 42 days. In how many days could both do it? |
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Answer» Answer: If they worked together from the beginning, they would NEED 30 DAYS to complete the WORK. Step-by-step explanation: Let the total amount of work is 1 UNIT. In 80 days A alone does 1 unit amount of work. In 1 day A alone does 1/80 unit amount of work. So, in 10 days A alone does 10/80 unit = 1/8 unit amount of work. After 10 days of working of A alone the REMAINING amount of work is (1 - 1/8) = 7/8 unit of work. In 42 days B alone does 7/8 unit amount of work. So, in 1 day B alone does 7/(8*42) unit = 1/48 unit amount of work. In 1 day A and B together do [(1/80) + (1/48)] unit = 1/30 unit amount of work. 1/30 unit amount of work is done in 1 day when A and B work together. So, total work = 1 unit amount of work is done in 30 days when A and B work together. |
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