It is currently 17 Dec 2017, 06:03

Close

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
Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

There are 4 quarts in a gallon. A gallon of motor oil sells for $12

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Expert Post
1 KUDOS received
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 42648

Kudos [?]: 135946 [1], given: 12716

There are 4 quarts in a gallon. A gallon of motor oil sells for $12 [#permalink]

Show Tags

New post 16 Oct 2017, 09:21
1
This post received
KUDOS
Expert's post
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

79% (01:10) correct 21% (01:18) wrong based on 70 sessions

HideShow timer Statistics

There are 4 quarts in a gallon. A gallon of motor oil sells for $12 and a quart of the same oil sells for $5. The owner of a rental agency has 6 machines and each machine needs 5 quarts of oil. What is the minimum amount of money she must spend to purchase enough oil?

(A) $84
(B) $94
(C) $96
(D) $102
(E) $150
[Reveal] Spoiler: OA

_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Kudos [?]: 135946 [1], given: 12716

Intern
Intern
avatar
Joined: 12 Oct 2017
Posts: 3

Kudos [?]: 11 [0], given: 2

Re: There are 4 quarts in a gallon. A gallon of motor oil sells for $12 [#permalink]

Show Tags

New post 16 Oct 2017, 09:39
1
This post was
BOOKMARKED
6 machines need 6 x 5 = 30 quarts of oil, which equals 7 gallons and 2 quarts.
We need to calculate as many gallons all the machines need as possible since the price of 1 gallon is obviously cheaper than that of 4 quarts.

Hence, the minimum amount of money she must spend to purchase enough oil is: (7x$12) + (2x$5) = $94

Answer: B

Kudos [?]: 11 [0], given: 2

Intern
Intern
avatar
B
Joined: 10 Jun 2016
Posts: 24

Kudos [?]: 7 [0], given: 281

Premium Member
Re: There are 4 quarts in a gallon. A gallon of motor oil sells for $12 [#permalink]

Show Tags

New post 16 Oct 2017, 09:56
Bunuel wrote:
There are 4 quarts in a gallon. A gallon of motor oil sells for $12 and a quart of the same oil sells for $5. The owner of a rental agency has 6 machines and each machine needs 5 quarts of oil. What is the minimum amount of money she must spend to purchase enough oil?

(A) $84
(B) $94
(C) $96
(D) $102
(E) $150


4 quarts make a gallon.

1 gallon of motor oil costs $12, which means 4 quarts (in the gallon) cost $12. This implies, if bought in a gallon quantity, one quart of oil will cost $3. Therefore, to minimise the cost, the customer must maximise the quantity in gallons she buys and reduce the quantity in quarts.

6 machines with each machine consuming 5 quarts totally consume 30 quarts of oil.

To minimise the cost, the maximum quantity she could buy in gallons is 28 (largest integer less than 30 that is divisible by 4). This leaves 2 quarts to be bought individually.

Therefore, minimum cost = $(7*12) + $(2*5) = $94.

Thus, B.

Kudos [?]: 7 [0], given: 281

Intern
Intern
avatar
Joined: 25 Apr 2017
Posts: 3

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

There are 4 quarts in a gallon. A gallon of motor oil sells for $12 [#permalink]

Show Tags

New post 16 Oct 2017, 10:34
total oil required = 6(machines)*5(q/machine) = 30 q
since 1 gallon = 4 quarts
30 quarts = 7g+2q
7g*$12/g+2q*$5/q = 94 $

ans- $94 (b)

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

1 KUDOS received
Manager
Manager
User avatar
B
Joined: 09 Aug 2017
Posts: 59

Kudos [?]: 8 [1], given: 18

Location: United States
Concentration: Technology
GMAT 1: 640 Q44 V33
GMAT 2: 630 Q47 V29
WE: Research (Investment Banking)
Re: There are 4 quarts in a gallon. A gallon of motor oil sells for $12 [#permalink]

Show Tags

New post 23 Oct 2017, 07:10
1
This post received
KUDOS
I got B. I checked my answer multiple ways to ensure I didn’t make a silly mistake which has hampered my practice tests. I might be close to a 48 or 50 if it weren’t for the five or six problems where I do something stupid like misread a question or flip a sign.
First, I read the question stem at the very end of the question. We need to figure out the minimum money this person needs to purchase enough oil.
- She needs 30 quarts since 6 machines require 5 quarts each. (6*5=30)
- 7 gallons will get her 28 quarts which costs $84.
- She’ll need to buy two more quarts which costs $10. 84+10=94.
- I checked to see if it’d be cheaper to buy 8 gallons, but that costs 96.
_________________

I'd love to hear any feedback or ways to improve my problem solving. I make a lot of silly mistakes. If you've had luck improving on stupid mistakes, I'd love to hear how you did it.

Also, I appreciate any kudos.

Kudos [?]: 8 [1], given: 18

VP
VP
avatar
P
Joined: 22 May 2016
Posts: 1137

Kudos [?]: 407 [0], given: 647

There are 4 quarts in a gallon. A gallon of motor oil sells for $12 [#permalink]

Show Tags

New post 23 Oct 2017, 14:03
Bunuel wrote:
There are 4 quarts in a gallon. A gallon of motor oil sells for $12 and a quart of the same oil sells for $5. The owner of a rental agency has 6 machines and each machine needs 5 quarts of oil. What is the minimum amount of money she must spend to purchase enough oil?

(A) $84
(B) $94
(C) $96
(D) $102
(E) $150

Approach I - Remainder
I treated this as a remainder question.

She needs 30 quarts of oil:
6 machines * 5 quarts ea = 30 quarts

1 gallon = 4 quarts

Divide 30 by 4.

Because there are 4 quarts in one gallon, the division will yield the number of gallons plus leftover quarts --

That is, the remainder will be quarts that don't "fit" and have to be bought separately.

\(\frac{30}{4}\) = 7 + R2 (quarts)
(7 gallons * $12 per gallon) = $84
(2 quarts * $5 per quart) = $10

$84 +10 = $94 is the minimum

Answer B

Approach II - Conversion, units will cancel

M = machines
Q = quarts
G = gallons

\((6M *\frac{5Q}{1M}*\frac{1G}{4Q})= \frac{30G}{4}= 7\frac{2}{4}G\)

7 gallons plus
\(\frac{2}{4}\) of a gallon
1 gallon=\(\frac{4}{4}\) quarts
You need 2 of those 4 quarts.

Then multiply 7 gallons and 2 quarts by cost per each, and sum, as above.

Minimum is $94

Answer B

Kudos [?]: 407 [0], given: 647

There are 4 quarts in a gallon. A gallon of motor oil sells for $12   [#permalink] 23 Oct 2017, 14:03
Display posts from previous: Sort by

There are 4 quarts in a gallon. A gallon of motor oil sells for $12

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.