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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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Answer:

They will work for
17(1)/(7) minute
\simeq 17.14 minute together to finish the work.

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 * 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
(1)/(60) of the total work.

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


(1)/(45) +(1)/(60)

=
(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
(2)/(3) of the total work in


(180 * 2)/(3 * 7) minute

=
(120)/(7) minute

=
17(1)/(7) minute


\simeq 17.14 minute

User Unkas
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