Question

    Two people, A and B, working separately can sanitize a building in 6 and 10 hours, respectively. They work in stretches of one hour alternately. If A begins at 8 a.m., then when will the work be finished?

    A 11/2hours Correct Answer Incorrect Answer
    B 22/3hours Correct Answer Incorrect Answer
    C 15/4hours Correct Answer Incorrect Answer
    D 6/5hours Correct Answer Incorrect Answer

    Solution

    A                            B 6                            10                30                         (Total work) 5                            3             -Efficiency Working fashion ® (A, B, A, B.) 2 hours ® 8 units   6 hours ® 24 units 7 hours ® 29 units 8 hours ® 1/ 3 hours ® 30 units Total time ® 22/3 hours   Þ Work will finish.

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