Sue can clean the room in 45 minutes. Ann can clean the room in 1 hour. Sue cleaned for 15 minutes before Ann came to help her. How long did

Question

Sue can clean the room in 45 minutes. Ann can clean the room in 1 hour. Sue cleaned for 15 minutes before Ann came to help her. How long did they work together to finish cleaning? Write answer in fraction then write in decimal.

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Serenity 1 week 2021-11-20T18:23:14+00:00 1 Answer 0

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    2021-11-20T18:25:12+00:00

    Answer:

    They will work for 17\dfrac{1}{7} minute \simeq 17.14 minute  together to finish the work.

    Step-by-step explanation:

    In 45 minutes Sue cleans the whole room

    So, in 1 minute Sue does \frac {1}{45} part of the total work ——-(1)

    so in 15 minutes Sue does \frac {1 \times 15}{45}

                        = \frac {1}{3} part of the total work ————————-(2)

    So, the amount of work left, = (1 – 1/3)  

                                                  = 2/3 of the total work.

    In 60 minutes, Ann cleans the whole room

    so,in 1 minute Ann does \frac{1}{60} of the total work.

    So, in 1 minute, Ann and Sue together do,

                                                        \frac{1}{45} +\frac{1}{60}

                                                        = \frac{4 + 3}{180}

                                                        = \frac {7}{180}  of the total work.

    So, Ann and Sue together do \frac {7}{180}  of the total work in 1 minute.

    So, they would have done  the whole work in, \frac {180}{7} minute.

    So, they would do \frac{2}{3} of the total work in

      \frac{180 \times 2}{3 \times 7} minute

      = \frac{120}{7} minute

      = 17\dfrac{1}{7} minute

      \simeq 17.14 minute

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