Gmat prep 1 Ques

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Gmat prep 1 Ques

by abhinav85 » Mon Jun 01, 2009 7:20 pm
If the speed of x metres per second is equivalent to the speed of y kilometres per hour , what is y in terms of x?
(1 kilometers = 1000 metres).

A) 5x/18

B) 6x/5

C) 18x/5

D) 60x

E) 3600,000x.

C

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Re: Gmat prep 1 Ques

by kvamsy » Mon Jun 01, 2009 8:13 pm
X/S = Y*1000/3600S

Y = 3600X/10^3

Y = 18X/5

answer c

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by tj123 » Mon Jun 01, 2009 9:36 pm
please elaborate your answer.

i get the following

1000x/60 = y/3600

3600(1000)x / 60 = y

60000x = y

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by abhinav85 » Tue Jun 02, 2009 4:52 am
can u explain this how did u get this equation?

X/S = Y*1000/3600S !!!

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by sacx » Tue Jun 02, 2009 6:27 am
When you need to convert Km/hr into m/s multiply it by 5/18

eg: 36 km/hr = 36 *5/18 = 10 mps

When you need to convert m/s to km/hr multiply it by 18/5

eg: 20 m/s = 20 * 18/5 = 72 km/hr
SACX

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by tj123 » Tue Jun 02, 2009 9:24 pm
thanks for the quick reference, but im still not clear on how this was dervied
X/S = Y*1000/3600S

specifically why is 1000 multiplied by y

please dervie this equation in detail
thanks

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by bumblenbumble01 » Wed Jun 03, 2009 8:48 am
hope this might clear it up:
the speed of y is km/hour and you know that 1km=1,000m. you also know that 1 hour is equal to 3600 seconds.

km--> x/1000
hr--> 3600

so y= [x/1000]/3600 --> multiply x/1000 by 3600/1 --> 3600x/1000 and simplify for 18x/5

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by vpmba2009 » Wed Jun 03, 2009 9:40 am
"x meters per second is equivalent to the speed of y kilometers per hour"means x/1"second" = y/1 "hour" (*)
We know that 1kilometer = 1000 meters and that 1 hour = 3600 seconds
Therefore, (*) can be written as x/1000 * 1"second" = y/3600 seconds
=> y=3600x/1000 = 18x/5
You can take a real number and try to convert it in to m/s or km/h, then you will figure out

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by tj123 » Wed Jun 03, 2009 9:56 pm
thanks.

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its all conversion

by arsinteco2005 » Wed Jun 03, 2009 11:32 pm
60*60*x=1000y

18/5x=y

answer C