It is currently 18 Jan 2018, 04:08

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Recently, fuel price has seen a hike of 20%. Mr X is planning to buy

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 43320

Kudos [?]: 139373 [0], given: 12787

Recently, fuel price has seen a hike of 20%. Mr X is planning to buy [#permalink]

### Show Tags

07 Jul 2017, 01:06
Expert's post
12
This post was
BOOKMARKED
00:00

Difficulty:

65% (hard)

Question Stats:

63% (01:29) correct 37% (01:42) wrong based on 399 sessions

### HideShow timer Statistics

Recently, fuel price has seen a hike of 20%. Mr X is planning to buy a new car with better mileage as compared to his current car. By what % should the new mileage be more than the previous mileage to ensure that Mr X’s total fuel cost stays the same for the month? (assuming the distance traveled every month stays the same)[/b]

(A) 10%
(B) 17%
(C) 20%
(D) 21%
(E) 25%
[Reveal] Spoiler: OA

_________________

Kudos [?]: 139373 [0], given: 12787

Manager
Joined: 14 Oct 2015
Posts: 226

Kudos [?]: 102 [1], given: 597

Recently, fuel price has seen a hike of 20%. Mr X is planning to buy [#permalink]

### Show Tags

07 Jul 2017, 02:18
1
KUDOS
3
This post was
BOOKMARKED
Bunuel wrote:
Recently, fuel price has seen a hike of 20%. Mr X is planning to buy a new car with better mileage as compared to his current car. By what % should the new mileage be more than the previous mileage to ensure that Mr X’s total fuel cost stays the same for the month? (assuming the distance traveled every month stays the same)[/b]

(A) 10%
(B) 17%
(C) 20%
(D) 21%
(E) 25%

Lets say Price and Mileage before hike are P1 and M1 respectively. After Hike, they are P2 and M2 respectively.

If price per mile is to stay the same, we need to have this equation.

$$P1 / M1 = P2 / M2$$

$$M2 = P2 * M1/P1$$

but P2 is 1.2 times P1.

$$P1 / M1 = 1.2P1 / M2 * P1$$

$$M2 = 1.2M1$$

Difference is 1.2 or 20%.

Edit: Editing after mistake was pointed out by chetan2u
_________________

Please hit Kudos if this post helped you inch closer to your GMAT goal.
Procrastination is the termite constantly trying to eat your GMAT tree from the inside.
There is one fix to every problem, working harder!

Last edited by jedit on 07 Jul 2017, 19:51, edited 2 times in total.

Kudos [?]: 102 [1], given: 597

Math Expert
Joined: 02 Aug 2009
Posts: 5522

Kudos [?]: 6419 [3], given: 122

Recently, fuel price has seen a hike of 20%. Mr X is planning to buy [#permalink]

### Show Tags

07 Jul 2017, 02:42
3
KUDOS
Expert's post
jedit wrote:
Bunuel wrote:
Recently, fuel price has seen a hike of 20%. Mr X is planning to buy a new car with better mileage as compared to his current car. By what % should the new mileage be more than the previous mileage to ensure that Mr X’s total fuel cost stays the same for the month? (assuming the distance traveled every month stays the same)[/b]

(A) 10%
(B) 17%
(C) 20%
(D) 21%
(E) 25%

Lets say Price and Mileage before hike are P1 and M1 respectively. After Hike, they are P2 and M2 respectively.

We need them to be Equal.

$$P1 * M1 = P2 * M2$$

Hi..
We have to be very careful while making the equation
Even the Q tells you that the new mileage INCREASE, so the increase cannot be together both in P and M as the equation taken by you..

What is mileage? D/L...
D is same ..

So $$\frac{P_1}{M_1}=\frac{P_2}{M_2}.......m_2=\frac{p_2*m_1}{p_1}$$
Ans 20%
C
_________________

Absolute modulus :http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html

BANGALORE/-

Kudos [?]: 6419 [3], given: 122

Intern
Joined: 23 Feb 2017
Posts: 37

Kudos [?]: 1 [0], given: 8

Re: Recently, fuel price has seen a hike of 20%. Mr X is planning to buy [#permalink]

### Show Tags

07 Jul 2017, 18:30
lets take 1 gallon of gas - 10$- gives 30miles same eq : 1 gallon of gas - 12$ - give x miles to breakeven.
12*30/10 = 36 , so miles should increase by 6 means 20% increase.
Ans C.

Kudos [?]: 1 [0], given: 8

Manager
Joined: 20 Jun 2014
Posts: 53

Kudos [?]: 15 [0], given: 24

GMAT 1: 630 Q49 V27
GMAT 2: 660 Q49 V32
Re: Recently, fuel price has seen a hike of 20%. Mr X is planning to buy [#permalink]

### Show Tags

07 Jul 2017, 23:31
1
This post was
BOOKMARKED
Total cost initially = C * fuel => C * Distance/mileage ( mileage = distance/litre)
Let initial mileage be m1 and later mileage be m2
Later cost = 1.2C* Distance/m2
Cost has to remain same => C*D/m1 = 1.2 C* D/m2
=>m2 = 1.2m1 => 20% increase in mileage
IMO C

Kudos [?]: 15 [0], given: 24

Manager
Joined: 30 May 2012
Posts: 217

Kudos [?]: 87 [0], given: 151

Location: United States (TX)
Concentration: Finance, Marketing
GPA: 3.3
WE: Information Technology (Consulting)
Re: Recently, fuel price has seen a hike of 20%. Mr X is planning to buy [#permalink]

### Show Tags

10 Jul 2017, 22:09

Kudos [?]: 87 [0], given: 151

Target Test Prep Representative
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 1820

Kudos [?]: 1048 [4], given: 5

Re: Recently, fuel price has seen a hike of 20%. Mr X is planning to buy [#permalink]

### Show Tags

12 Jul 2017, 15:36
4
KUDOS
Expert's post
Bunuel wrote:
Recently, fuel price has seen a hike of 20%. Mr X is planning to buy a new car with better mileage as compared to his current car. By what % should the new mileage be more than the previous mileage to ensure that Mr X’s total fuel cost stays the same for the month? (assuming the distance traveled every month stays the same)[/b]

(A) 10%
(B) 17%
(C) 20%
(D) 21%
(E) 25%

Since the fuel price is directly proportional to mileage of a car; if the fuel price is increased by 20%, the mileage of the car should be increased by 20% as well to keep the total fuel cost the same.

_________________

Jeffery Miller

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Kudos [?]: 1048 [4], given: 5

Intern
Joined: 22 Oct 2016
Posts: 22

Kudos [?]: 4 [0], given: 23

Re: Recently, fuel price has seen a hike of 20%. Mr X is planning to buy [#permalink]

### Show Tags

20 Jul 2017, 04:10
chetan2u wrote:
jedit wrote:
Bunuel wrote:
Recently, fuel price has seen a hike of 20%. Mr X is planning to buy a new car with better mileage as compared to his current car. By what % should the new mileage be more than the previous mileage to ensure that Mr X’s total fuel cost stays the same for the month? (assuming the distance traveled every month stays the same)[/b]

(A) 10%
(B) 17%
(C) 20%
(D) 21%
(E) 25%

Lets say Price and Mileage before hike are P1 and M1 respectively. After Hike, they are P2 and M2 respectively.

We need them to be Equal.

$$P1 * M1 = P2 * M2$$

Hi..
We have to be very careful while making the equation
Even the Q tells you that the new mileage INCREASE, so the increase cannot be together both in P and M as the equation taken by you..

What is mileage? D/L...
D is same ..

So P1/M1=P2/M2.......m2=p2*m1p1
Ans 20%
C

Hi Chetan2u,

I guess you mentioned to say, m2 = p2*(m1/p1)

_________________

Regards,
Sarugiri

Kudos [?]: 4 [0], given: 23

Manager
Status: love the club...
Joined: 24 Mar 2015
Posts: 232

Kudos [?]: 28 [0], given: 481

Re: Recently, fuel price has seen a hike of 20%. Mr X is planning to buy [#permalink]

### Show Tags

30 Aug 2017, 08:26
jedit wrote:
Bunuel wrote:
Recently, fuel price has seen a hike of 20%. Mr X is planning to buy a new car with better mileage as compared to his current car. By what % should the new mileage be more than the previous mileage to ensure that Mr X’s total fuel cost stays the same for the month? (assuming the distance traveled every month stays the same)[/b]

(A) 10%
(B) 17%
(C) 20%
(D) 21%
(E) 25%

Lets say Price and Mileage before hike are P1 and M1 respectively. After Hike, they are P2 and M2 respectively.

If price per mile is to stay the same, we need to have this equation.

$$P1 / M1 = P2 / M2$$

$$M2 = P2 * M1/P1$$

but P2 is 1.2 times P1.

$$P1 / M1 = 1.2P1 / M2 * P1$$

$$M2 = 1.2M1$$

Difference is 1.2 or 20%.

Edit: Editing after mistake was pointed out by chetan2u

hi

can you, however, apply the same logic to the following problem ....??

The cost of fuel increases by 10%. By what % must the consumption of fuel decrease to keep the overall amount spent on the fuel same?

(A) 5%
(B) 9%
(C) 10%
(D) 11%
(E) 20%

Kudos [?]: 28 [0], given: 481

Intern
Joined: 21 Sep 2016
Posts: 28

Kudos [?]: 2 [0], given: 261

Recently, fuel price has seen a hike of 20%. Mr X is planning to buy [#permalink]

### Show Tags

13 Sep 2017, 07:18
Let's assume you can drive 100 miles at a cost of 1000 usd.
Because of the price increase, you now have to spend 1200 usd to drive the same mileage.

That means you used to spend 10 usd per mile, now you spend 12.

So, let M2 be the requested mileage so that the price per mile remains at 10 usd:

$$1200/M2 = 10$$

$$M2 = 120$$

$$(120-100)/100 = 0.2$$

Thus answer C is the right one.

Kudos [?]: 2 [0], given: 261

BSchool Forum Moderator
Joined: 26 Feb 2016
Posts: 1802

Kudos [?]: 824 [2], given: 22

Location: India
WE: Sales (Retail)
Recently, fuel price has seen a hike of 20%. Mr X is planning to buy [#permalink]

### Show Tags

13 Sep 2017, 07:40
2
KUDOS
This problem becomes a lot easier when we assume numbers.

If we were buying 1 unit fuel worth 100$and the old car was offering a mileage of 10 miles/gallon, it would cost us 10$ to drive a mile

Since the price has gone up by 20%, the fuel will now cost 120$. If he needs to spend the same amount per miles driven, Let the mileage of the new car be x Therefore, $$\frac{120}{x} = 10$$ $$x = 12$$(which is a 20% increase over 10$/galon) (Option C)
_________________

Stay hungry, Stay foolish

Kudos [?]: 824 [2], given: 22

Intern
Joined: 23 Sep 2017
Posts: 14

Kudos [?]: 0 [0], given: 27

Re: Recently, fuel price has seen a hike of 20%. Mr X is planning to buy [#permalink]

### Show Tags

31 Oct 2017, 01:55
pushpitkc wrote:
This problem becomes a lot easier when we assume numbers.

If we were buying 1 unit fuel worth 100$and the old car was offering a mileage of 10 miles/gallon, it would cost us 10$ to drive a mile

Since the price has gone up by 20%, the fuel will now cost 120$. If he needs to spend the same amount per miles driven, Let the mileage of the new car be x Therefore, $$\frac{120}{x} = 10$$ $$x = 12$$(which is a 20% increase over 10$/galon) (Option C)

Make sense ^^
Thank you for your explanation +1 Kudos

Kudos [?]: 0 [0], given: 27

Senior Manager
Joined: 03 Apr 2013
Posts: 292

Kudos [?]: 52 [0], given: 862

Location: India
Concentration: Marketing, Finance
Schools: Simon '20
GMAT 1: 740 Q50 V41
GPA: 3
Re: Recently, fuel price has seen a hike of 20%. Mr X is planning to buy [#permalink]

### Show Tags

01 Dec 2017, 06:03
Bunuel wrote:
Recently, fuel price has seen a hike of 20%. Mr X is planning to buy a new car with better mileage as compared to his current car. By what % should the new mileage be more than the previous mileage to ensure that Mr X’s total fuel cost stays the same for the month? (assuming the distance traveled every month stays the same)[/b]

(A) 10%
(B) 17%
(C) 20%
(D) 21%
(E) 25%

Hi, please explain whether mileage is miles/gallon or dollars/mile?

Please also help to solve this question in the most efficient manner.
VeritasPrepKarishma your help is greatly appreciated.
_________________

Spread some love..Like = +1 Kudos

Kudos [?]: 52 [0], given: 862

Manager
Joined: 23 Oct 2017
Posts: 63

Kudos [?]: 2 [0], given: 4

Re: Recently, fuel price has seen a hike of 20%. Mr X is planning to buy [#permalink]

### Show Tags

05 Jan 2018, 20:18
ShashankDave wrote:
Bunuel wrote:
Recently, fuel price has seen a hike of 20%. Mr X is planning to buy a new car with better mileage as compared to his current car. By what % should the new mileage be more than the previous mileage to ensure that Mr X’s total fuel cost stays the same for the month? (assuming the distance traveled every month stays the same)[/b]

(A) 10%
(B) 17%
(C) 20%
(D) 21%
(E) 25%

Hi, please explain whether mileage is miles/gallon or dollars/mile?

Please also help to solve this question in the most efficient manner.
VeritasPrepKarishma your help is greatly appreciated.

---------------------------

This can be seen as a problem with 2 inverse variations:
1. Since Mr.X want to be keep his fuel cost = const , the fuel hike would mean low fuel consumption i.e
cost = fuel price * fuel consumption = constant
after 20% hike, new fuel price = (fuel price)*(120/100) ---(a)
(fuel price) * (fuel consumption) = (new fuel price)*(fuel consumption)
On substituting (a) in the above, we get:
=> new fuel consumption = (fuel consumption) 100/120 {meaning fuel consumption has decreased now)

2. Next is about mileage, now Mr.X wants better mileage to handle the decreased fuel consumption

(old Mileage) * (fuel consumption) = (new mileage) * (new fuel consumption)

since new fuel consumption = (fuel consumption) 100/120

new mileage = (old mileage) * 120/100 => indicating a 20 % increase needed in mileage

Kudos [?]: 2 [0], given: 4

Re: Recently, fuel price has seen a hike of 20%. Mr X is planning to buy   [#permalink] 05 Jan 2018, 20:18
Display posts from previous: Sort by