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    Question

    If a task can be completed by

    either 10 boys or 12 girls in 10 days, how long will it take for a team of 5 boys and 2 girls working together to finish the same task?
    A 18 days Correct Answer Incorrect Answer
    B 12 days Correct Answer Incorrect Answer
    C 15 days Correct Answer Incorrect Answer
    D 22 days Correct Answer Incorrect Answer

    Solution

    ATQ,

    Let efficiency of a boy and a girl is ‘M’ units per day and ‘W’ units per day respectively. Total task = 10 × 12 × W = 120W units And, 10M = 12W Or, 5M = 6W Efficiency of 5 boys and 2 girls = 5M + 2W = 6W + 2W = 8W units per day Desired time = 120W/8W = 15 days 

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