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# Lindsay can paint 1/x of a certain room in 20 minutes. What fraction

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Senior Manager
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Lindsay can paint 1/x of a certain room in 20 minutes. What fraction  [#permalink]

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05 Nov 2011, 13:25
7
00:00

Difficulty:

45% (medium)

Question Stats:

69% (02:32) correct 31% (02:54) wrong based on 94 sessions

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Lindsay can paint 1/x of a certain room in 20 minutes. What fraction of the same room can Joseph paint in 20 minutes if the two of them can paint the room in an hour, working together at their respective rates?

A)1/3x
B) 3x/(x – 3)
C) (x – 3) / 3x
D)x / (x – 3)
E) (x – 3) / x

OPEN DISCUSSION OF THIS QUESTION IS HERE: https://gmatclub.com/forum/lindsay-can- ... 56880.html

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Re: Lindsay can paint 1/x of a certain room in 20 minutes. What fraction  [#permalink]

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05 Nov 2011, 14:00
1
Lindsay ->
paints 1/x of a certain room in 20 minutes or 1/3 hour,
Hence, whole room can be painted in (1/3)/(1/x) = (x/3) Hour.

Joseph ->
Lets say paints 1/y of a certain room in 20 minutes or 1/3 hour. (We have to find y in terms of x)
Hence, whole room can be painted in (1/3)/(1/y) = (y/3) Hour.

As question says, two of them can paint the room in an hour
Hence, 1/(x/3)+ 1/(y/3)= 1 hr
Simpfying for y we -> y = 3x/(x-3)

Hope it helps.
Cheers!
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Re: Lindsay can paint 1/x of a certain room in 20 minutes. What fraction  [#permalink]

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05 Nov 2011, 21:51
1
enigma123 wrote:
Lindsay can paint 1/x of a certain room in 20 minutes. What fraction of the same room can Joseph paint in 20 minutes if the two of them can paint the room in an hour, working together at their respective rates?

A)1/3x
B) 3x/(x – 3)
C) (x – 3) / 3x
D)x / (x – 3)
E) (x – 3) / x

Correct answer is C. Any idea how to solve this guys?

Lindsey and Joseph together can paint the room in 1 hour

in 20 mins they can paint 1/3 part of the room.

Lindsay alone paints 1/x part of the room in 20 mins

Take Joseph paints 1/y parts in 20 mins

1/x + 1/y = 1/3

1/y = 1/3 - 1/x = (x-3)/3x ANs C
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Re: Lindsay can paint 1/x of a certain room in 20 minutes. What fraction  [#permalink]

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18 Dec 2017, 23:43
1
1
Lindsay can paint 1/x of a certain room in 20 minutes. What fraction of the same room can Joseph paint in 20 minutes if the two of them can paint the room in an hour, working together at their respective rates?

A. $$\frac{1}{3x}$$

B. $$\frac{3x}{(x – 3)}$$

C. $$\frac{(x – 3)}{3x}$$

D. $$\frac{x}{(x – 3)}$$

E. $$\frac{(x – 3)}{x}$$

Since Lindsay can paint $$\frac{3}{x}$$ of a room in 1 hour and together they paint the whole room in 1 hour then Joseph can paint $$1-\frac{3}{x}=\frac{x-3}{x}$$ of a room in 1 hour --> in 20 minute or in $$\frac{1}{3}$$ of an hour Joseph can paint $$\frac{x-3}{3x}$$ of a room.

Similar question: https://gmatclub.com/forum/lindsay-can- ... 98789.html

OPEN DISCUSSION OF THIS QUESTION IS HERE: https://gmatclub.com/forum/lindsay-can- ... 56880.html
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Re: Lindsay can paint 1/x of a certain room in 20 minutes. What fraction   [#permalink] 18 Dec 2017, 23:43
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