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**Hamster****Member**- Registered: 2005-05-18
- Posts: 1

Paula can clan the room in 3 hours. Paula and Maria can clean it in 2 hours. How long would it take Maria working alone to clean the room.

Thanks.

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**Zach****Member**- Registered: 2005-03-23
- Posts: 2,075

6 hours if it's dirty again in exactly the same way.

Something awefully strange is going on.

*Last edited by Zach (2005-05-18 21:30:35)*

Boy let me tell you what:

I bet you didn't know it, but I'm a fiddle player too.

And if you'd care to take a dare, I'll make a bet with you.

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,651

Let's look at how much they can do per hour (their "cleaning-up rate")

Paula is be able to clean 1/3rd of the room per hour. (1/3rd of a room times 3 hours = 1 room)

Paula and Maria together can clean 1/2 a room per hour.

So Maria's contribution is to speed things up from 1/3rd per hour to 1/2 per hour.

Let's calculate how much of an increase that is: 1/2 - 1/3 = 3/6 - 2/6 = (3-2)/6 = 1/6

So Maria is only really cleaning 1/6th of the room per hour.

So on her own it would be **6 hours**.

(Maria is either very thorough at cleaning, or her heart isn't in it.)

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**Vulcan****Member**- Registered: 2005-04-23
- Posts: 224

i cant be bothered working it out!

thanks for doing it for me!

one day, i couldn't find my hat

then it occured to me that i didn't have one

so i didn't where it!!!

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**raeann****Member**- Registered: 2005-07-29
- Posts: 2

Hamster wrote:

Paula can clan the room in 3 hours. Paula and Maria can clean it in 2 hours. How long would it take Maria working alone to clean the room.

Thanks.

What is the answer?

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**mathsyperson****Moderator**- Registered: 2005-06-22
- Posts: 4,900

Zach and MathsIsFun both already said that it was 6 hours.

Why did the vector cross the road?

It wanted to be normal.

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