Gmat prep 1 Ques

X/S = Y*1000/3600S

Y = 3600X/10^3

Y = 18X/5

answer c

please elaborate your answer.

i get the following

1000x/60 = y/3600

3600(1000)x / 60 = y

60000x = y

can u explain this how did u get this equation?

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

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

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

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

"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

thanks.

60*60*x=1000y

18/5x=y

answer C