Rate problem:Typist(Easy approach z needed..:)

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Two secrarties,Sally and lisa,type at even but diffrence paces.Sally is more expeienced and types 80 characters per minute.Lisa a beginner can type only 30 char per minute.On one day,Lisa starts typing before sally.At somepoint both have typed the same number of characters.Then both continue typing and sally types 800 more characters until her computer breaks down.Assuming Lisa does not take any break,How long in hours,Will it take her to finish typing the same number of characters?

a)53/180
b)4/9
c)13/18
d)15/23
e)5/18
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by Atekihcan » Fri Jun 07, 2013 3:03 am
When Sally's computer broke down, she has typed 800 characters more than Lisa.
So, Lisa has to work some extra minutes to type 800 extra characters.

Lisa types 30 characters in 1 minute.
So, Lisa will type 800 characters in 800/30 minutes = 800/(30*60) hours = 8/18 hours = 4/9 hours

Answer : B

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by mkdureja » Fri Jun 07, 2013 3:04 am
rkiran9 wrote:Two secrarties,Sally and lisa,type at even but diffrence paces.Sally is more expeienced and types 80 characters per minute.Lisa a beginner can type only 30 char per minute.On one day,Lisa starts typing before sally.At somepoint both have typed the same number of characters.Then both continue typing and sally types 800 more characters until her computer breaks down.Assuming Lisa does not take any break,How long in hours,Will it take her to finish typing the same number of characters?

a)53/180
b)4/9
c)13/18
d)15/23
e)5/18
When Sally computer breaks down, she has typed 800 characters more than Lisa.
To type same number of characters, Lisa has to type 800 characters.
Asked: How long will it take her to type these 800 characters?
Her speed is 30 c/m.
She'll take = 800/30 mins or 800/30*60 hrs = 8/18 = 4/9.

OA??

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by GMATGuruNY » Fri Jun 07, 2013 3:46 am
rkiran9 wrote:Two secrarties,Sally and lisa,type at even but diffrence paces.Sally is more expeienced and types 80 characters per minute.Lisa a beginner can type only 30 char per minute.On one day,Lisa starts typing before sally.At somepoint both have typed the same number of characters.Then both continue typing and sally types 800 more characters until her computer breaks down.Assuming Lisa does not take any break,How long in hours,Will it take her to finish typing the same number of characters?

a)53/180
b)4/9
c)13/18
d)15/23
e)5/18
Sally:
At some point both have typed the same number of characters.
Sally types 800 more characters until her computer breaks down
Time for Sally to type 800 characters = w/r = 800/80 = 10 minutes.

Lisa:
At some point both have typed the same number of characters.
Then BOTH continue typing.

In the 10 minutes taken by Sally to type 800 characters, the number of characters typed by Lisa = r*t = 30*10 = 300.
Remaining characters to be typed by Lisa = 800-300 = 500 characters.
Time for Lisa to type the 500 remaining characters = w/r = 500/30 = 50/3 minutes.

To convert minutes to hours, we multiply by 1/60:
(50/3)(1/60) = 5/18 hours.

The correct answer is E.
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