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Re: help solving problem [#permalink]
09 May 2010, 21:40

y=18/5x

meters-->km is a factor of 1000

seconds --> hrs is a factor of 3600 (or 60sec/min times 60min/hr)

3600/1000 = 18/5. Did I do this right?

Let me try slower:

Meters/sec times 1KM/1000meter =KM/sec; Km/sec times 60 sec/min times 60 min/hr =km/hr. so we divide by 1000 and multiply by 3600. Yep I think I got it.

Re: speed/conversion problem [#permalink]
13 Dec 2010, 23:48

For conversions try to understand the basic fundamental through the below explanation;

Example #1)

1 mile= 1.61km

so 15.7 miles =? km

Soln: PRINCIPLE/METHODOLOGY:

Convert the eqn to a fraction with the desired units on top and the given units on the bottom i.e. to convert from miles to kilometers you need a fraction with the desired units (KM in our case) on THE TOP and the given units (Miles) on THE BOTTOM.

= 1.61km/1mile

Now the solution becomes 15.7miles * 1.61 Km /1 mile = 25.3km (Note how the miles in the num & deno cancel and we are left with km - as what the question asked.Keep this principle in mind)

Example #2)

7miles/sec is how many miles / hour?

Soln: 1 hr= 3600 sec In the question given units (sec) are in the denominator of the original measurement, so seconds must be in the numerator of the conversion function.

1 hr= 3600 sec i.e 1=3600/1hr

7miles/sec x 3600 sec/hr =7x 3600 = 25000 miles /hr . (Note the seconds get cancelled)

Example#3)

12 cubic yards = how many cubic feet?

Given: 1 yard= 3 feet . i.e 1 =3feet/1 yard

Therefore 12 yd^3 * (3ft/1yd)^3 = 12 * 3^3 * yd^3 x ft^3 / yd^3 = 12 x 27 ft^3 (Note that the yd^3 gets cancelled out in Num & Deno)

= 324 ft^3 (Ans)

COMING BACK TO YOUR ORIGINAL QUESTION , solution as follows, x mtr/sec= y km/hour

Therefore in terms of x calculate as follows,

xmtr/sec * 60sec/1min * 60min/1hr * 1km/1000mtr

= 18x/5 (note how the mtr,sec & min cancell out in the numerator and denominator giving us what we required)

Re: speed/conversion problem [#permalink]
14 Dec 2010, 01:10

Expert's post

scorpio7 wrote:

Hey guys, was wondering if anyone could offer a way to solve this problem:

If the speed of X meters per second is equivalent to the speed of Y kilometers per hour, what is Y in terms of X? (1 kilometer=1000 meters)

A. 15x/18 B. 6x/5 C. 18x/5 D. 60x E. 3600000x

answer: C.

X meters per second --> --> 3,600X meters per hour (as there are 3,600 seconds in one hour); --> 3,600X/1,000=18X/5 kilometers per hour (as there are 1,000 meters in one kilometer).

Answer: C.

Or if you are not comfortable with above manipulations with variable X then you can assume x to be equal to some #: let x=10.

Speed = 10 meters per second --> --> 10*3,600=36,000 meters per hour --> --> 36,000/1000=36 kilometers per hour.

So, if x=10, then y=36. Plug x=10 into the answer choices, the one which give 36 will be the correct answer: A. 15x/18=150/18<36; B. 6x/5=60/5=12; C. 18x/5=36 correct choice; D. 60x=600; E. 3,600,000x=36,000,000.

Re: If the speed of X meters per second is equivalent to the spe [#permalink]
30 Sep 2013, 11:48

can some expert give me some questions/links on this forum which involves unit conversions, Spl typical DS question types containing manipulation of speed units to arrive at answers. Have exam in less than a week, any help is appreciated. I tried searching the forum with keyword as "unit conversion" but didnt get what i am looking for _________________

Life is very similar to a boxing ring. Defeat is not final when you fall down… It is final when you refuse to get up and fight back!

Re: If the speed of X meters per second is equivalent to the spe [#permalink]
30 Sep 2013, 19:08

1

This post received KUDOS

Expert's post

nikhil007 wrote:

can some expert give me some questions/links on this forum which involves unit conversions, Spl typical DS question types containing manipulation of speed units to arrive at answers. Have exam in less than a week, any help is appreciated. I tried searching the forum with keyword as "unit conversion" but didnt get what i am looking for

Re: If the speed of X meters per second is equivalent to the spe [#permalink]
01 Oct 2013, 00:13

1

This post received KUDOS

Expert's post

nikhil007 wrote:

can some expert give me some questions/links on this forum which involves unit conversions, Spl typical DS question types containing manipulation of speed units to arrive at answers. Have exam in less than a week, any help is appreciated. I tried searching the forum with keyword as "unit conversion" but didnt get what i am looking for