If a car moving at the speed of x km/hr travels a distance

Question

If a car moving at the speed of x km/hr travels a distance of y km, which of the following cannot be equal to the distance traveled?

A. x-y km
B. x/2 km
C. (x-y)/2 km
D. y/x km 
E. y-x km

blueseas · Answer

we have to equate each option to Y
FOR OPTION E
Y-X=Y
clearly it means x=0....not possible.
hence 
imo E

WholeLottaLove · Answer

If a car moving at the speed of x km/hr travels a distance of y km, which of the following cannot be  equal to the distance traveled ?

Speed = distance/time
x=d/t
x=y/t

x=60
y=120
t=2

This is a bit of a trick question. They are looking for you to set each answer choice equal to the distance (i.e. equal to y) In this case, each answer must be set to the distance traveled (i.e. y)

A. x-y km 
x-y=y
x=2y

B. x/2 km 
x/2=y
x=2y

C. (x-y)/2 km 
(x-y)/2 = y
(x-y)=2y
x=3y

D. y/x km 
y/x=y
y=xy
x=1

E. y-x km  
y-x=y
x=0

While I am not 100% as to why X couldn't be 0, every single answer choice has x=some value y or 1. E is the "odd man out" so to speak.

Why can't I plug in numbers to solve this problem? It seems like the perfect time to use the plug in technique to solve for the answer.

Thanks!

SVaidyaraman · Answer

x cannot be equal to zero because the car is moving and so has to have some speed. Equating to y is the natural way to solve this problem because you can then find what is impossible.

Plugging in values will be cumbersome for this problem because each choice is true only when y and x are related in a particular way. For example in choice 3 which is x-y / 2, if you chose x=60 and y =40, x-y / 2 =10 you might think that since the distance traveled comes out as different i.e., as 40 and 10, the choice is wrong. But it is actually true when x=3y. Finding the right values is very difficult.

So generally when it is the case that you may have to plug in many values to find whether a choice is correct or not, trying to plug in values and solve is not the right approach.

GauravSolanky · Answer

I have a very basic question. Why we are not considering quantity we are dealing with ?
How can we subtract distance with speed or vice-verse ?
Only possible functions should be y/x or x/y.Correct me if I am missing something.

EMPOWERgmatRichC · Answer

Hi All,

This question can be solved by TESTing VALUES, but there's a particular pattern that you have to recognize to make the work "easy."

We're not really limited by anything in this question, so X and Y can be anything. Under normal circumstances, I won't TEST the number 1 in PS questions (as it often leads to duplicate answers), but here it's a great option (since we're looking to eliminate 4 answers, multiple TESTs are going to be likely anyway).

We're given information on speed (X km/hour) and distance (Y km). We're asked which of the 5 answer choices CANNOT be the distance traveled.

IF....
X = 2 and Y = 1
Answers A (2-1 = 1) and B (2/2 = 1) are POSSIBLE. Eliminate A and B.

IF....
X = 3 and Y = 1
Answer C ( /2 = 1) is POSSIBLE. Eliminate C.

IF....
X = 1 and Y = 1
Answer D (1/1 = 1) is POSSIBLE. Eliminate D.

Final Answer:  E

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

shashankism · Answer

The question seems to be a tricky one. And it needs a different approach. It is very difficult to identify the correct approach in the first go.

Speed of the car = x km/hr
Distance = y km

Lets start equating each options. 
A. x-y = y -> x = 2y

B. x/2 = y -> x = 2y

C. (x-y)/2 = y -> x = 3y

D. y/x = y -> x =1

E. y-x = y -> x = 0

Since car is moving, so only option E seems impossible.

Answer E

ScottTargetTestPrep · Answer

The distance traveled is y km. We think the question asks for the expression that cannot be another way to express the distance traveled. Let’s analyze each answer choice.

A) x - y = y → x = 2y → This is fine as long as x is twice of y.

B) x/2 = y → x = 2y → This is fine since it’s same as choice A.

C) (x - y)/2 = y → x - y = 2y → x = 3y → This is fine as long as x is three times of y.

D) y/x = y → x = 1 → This is fine as long as x is 1.

E) y - x = y → x = 0 → This is not fine since the speed can’t 0 km/hr.

Answer: E

bumpbot · Answer

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If a car moving at the speed of x km/hr travels a distance

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