If the speed of X meters per second is equivalent to the speed of Y ki

Question

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. 5x/18
B. 6x/5
C. 18x/5
D. 60x
E. 3,600,000x

johnwesley · Accepted Answer

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=1000meters).

y*\frac{kilometers}{hour}=x*\frac{meters}{seconds}

y*\frac{1\;kilometer}{1\; hour}*\frac{1000 \;meters}{1 \;kilometer}*\frac{1\; hour}{3600 \;seconds}=x*\frac{meters}{seconds}

y*\frac{1000 \;meters}{3600 \;seconds}=x*\frac{meters}{seconds}  -------->  y=\frac{3600}{1000}*x=\frac{18}{5}*x

Answer C

Bunuel · Answer

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

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.

Answer: C.

Bunuel · Answer

danzig · Answer

Bunuel, is this a word problem or what tipe of problem is?
Do you have a link to find more of these problems, please?

WholeLottaLove · Answer

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)

We need to find an equation with x in the answer...
convert all measurements so they are alike (i.e. convert km to m, seconds to hours, etc)

Speed = x/t
x meters/second
(3600) x meters/hour

Speed = y/t
y KM/hour
Speed = y(1000m)/hour

y(1000meters)/hour = (3600) x meters/hour

y(1000)/1hour = x(3600) / 1 hour
y(1000) = x(3600)
y = 3.6x

Answer: C. 18x/5

PareshGmat · Answer

x meters in 1 second i.e

\frac{x}{1000}  Kms in 1 Second i.e

\frac{x}{1000}  Kms in  \frac{1}{60}  Minutes i.e

\frac{x}{1000}  Kms in  \frac{1}{3600}  Hour i.e

\frac{x}{1000} * 3600  in 1 Hr = Y

y = \frac{18x}{5}

Answer = C

ydmuley · Answer

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

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.

Answer: C.

EMPOWERgmatRichC · Answer

Hi All,

This question can be solved in a couple of different ways; you can use unit conversions or you can use TEST IT:

We're asked to convert X meters/second into Y kilometers/hour....

If X = 2, then...

2 meters/second = 
120 meters/minute = 
7200 meters/hour = 
7.2 kilometers/hour

So we need an answer that equals 7.2 when X = 2

Plugging 2 into each of the answers gives us...

A) 10/18 = 5/9 
B) 12/5 = 2.4 
C) 36/5 = 7.2 
D) 120 
E) 7,200,000

Final Answer:  C

GMAT assassins aren't born, they're made, 
Rich

JeffTargetTestPrep · Answer

There are 3,600 seconds in an hour and 1,000 meters in a kilometer. So, let’s convert y kilometers/hour to meters/second:
 
We can start by converting y kilometers to meters.
 
y kilometers = 1,000y meters
 
Next we can convert 1 hour to seconds.
 
1 hour = 3,600 seconds
 
Thus, y km/hr can be expressed as 1,000y/3,600 m/sec, or 5y/18 m/sec, after it’s simplified.
 
Since our two rates are equal, x = 5y/18. We need to solve this equation for y.
 
18x = 5y
 
18x/5 = y
 
Answer: C

Bunuel · Answer

Check other  Conversion problems  to practice in  Special Questions Directory .

Kinshook · Answer

Y km/hr = Y 1000 / 60*60 m/s = 5Y/18 m/s = X m/s
Y = 18X/5

IMO C

Basshead · Answer

When converting meters per second to kilometers per hour we multiply by 18/5.

When converting kilometers per hour to meters per second we multiply by 5/18.

Answer is C: 18x/5.

blanchif · Answer

Hello folks,

How can't we calculate from x like:

x*(1000/3600) = Y i.e final result is B)

I fell in the trap b/c i started converting on X side and not Y, so i found 18x/5 ..

I don't understand why it does not work if we convert from X and not from Y ...

Thanks a lot for your help !

Sabby · Answer

Hi  blanchif

I fell into the same trap and found a way to avoid it, you can proceed with the following reasoning :

We know that xm/s=yk/h
We want y in terms of x, and here is where the trap is set :
we have to work only on the y side as we want y in terms of x. In other words, we need to convert y in terms of x. For example x is in seconds so we need to turn y's hour into seconds which becomes 3600 seconds

xm/s=1000y/3600 
x=5y/18 
therefore y = 18x/5

EDIT:

Just to clarify why we can't do it the other way around: It's because here we want one hour into seconds, but you can't turn one second into hours.

abhik1213 · Answer

how did you get to know that Km/hr has to be converted into meters per second and not viceversa.

abhik1213 · Answer

how did you get to know that Km/hr has to be converted into meters per second and not viceversa.

Bunuel · Answer

You could’ve done it that way too.

x meters per second = 3,600x meters per hour = 3.6x kilometers per hour.

So y = 3.6x = (18/5) * x, which gives the same result.

AnishPassi · Answer

Observation:  All answer choices are expressions in terms of x. That means the x → y relationship is fixed. So if an expression is correct, it must work for any value of x. This makes  plugging-in  a safe way to eliminate wrong expressions.

Now, what value of x should I pick?
I want something that’s easy to work with and easy to convert into kilometers per hour. x=1 meter per second feels natural.

If speed is 1 meter/second, then in 1 second, we cover 1 meter. 
 In one hour, there are 3600 seconds, so that’s 3600 meters in an hour. 
 3600 meters = 3.6 kilometers.

So, 1 m/s = 3.6km/h.

That gives me a “target” for y: when x=1, y should be 3.6.

Test each option at x=1:

A.5x/18 → 5/18 → even less than 1. ❌ too small 
 B.6x/5 →6/5 → less than 2 ❌ too small 
 C.18x/5 →18/5 = 3.6. matches. keep. 
 D. 60x → 60 ❌ way too large 
 E. 3,600,000x → 3,600,000 ❌ absurd

Since we were able to eliminate 4 answers, the remaining choice - C - must be the correct answer.

Additional notes:

Why not mark (C) the moment it matched?
Because with plug-in, it’s possible for more than one expression to match your first test value by coincidence. If that happens, we can test a second test value to break the tie.

I’ll illustrate this with an extra hypothetical option.

Consider F. 18(x+1)/5x+5.

At x=1, F. 36/10=3.6 — it matches.

So, we could try another easy value of x (for which we can easily figure out the corresponding y value).

1 m/s =3.6 km/h
So, 
10 m/s = 36 km/h

Let’s plug-in x = 10 in C and F. The result should be 36.

C. 18x/5 → 180/5 = 36. Matches. Keep.

F. 18(x+1)/5x+5 → 18x11/55 = 18/5 =3.6. Doesn’t match. Rejected.

Also notice

F simplifies to:
18(x+1)/5(x+1) = 18/5 → a constant.
So, anyway a constant can’t be the correct answer. The value of y should change as x changes. That itself is also reason enough to reject F.

sujoykrdatta · Answer

Y km/hr 
means Y km ÷ 1 hour
means 1000Y m ÷ 60×60 sec
means 1000Y m ÷ 3600 sec
means 1000Y/3600 m/s
means 5Y/18 m/s
which is x m/s

=> x = 5Y/18 
=> Y = 18x/5

Option C

If the speed of X meters per second is equivalent to the speed of Y ki

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If the speed of X meters per second is equivalent to the speed of Y ki

Prep Toolkit

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