BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

how do i solve this

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 265
Joined: Tue Jul 03, 2012 11:04 pmFollowed by: 6 members
by grandh01 » Wed Aug 01, 2012 2:13 pm
11. If 6 gallons of gasoline are added to a tank that is already filled to 3/4 of its
capacity, the tank is then filled to 9/10 of its capacity. How many gallons does
the tank hold?
(A) 20
(B) 24
(C) 36
(D) 40
(E) 60

Thanks in advance
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
User avatar
Legendary Member
Posts: 520
Joined: Sat Apr 28, 2012 9:12 pmFollowed by: 49 members
Thanked: 339 times
GMAT Score:770

by eagleeye » Wed Aug 01, 2012 2:18 pm
grandh01 wrote:11. If 6 gallons of gasoline are added to a tank that is already filled to 3/4 of its
capacity, the tank is then filled to 9/10 of its capacity. How many gallons does
the tank hold?
(A) 20
(B) 24
(C) 36
(D) 40
(E) 60

Thanks in advance
Let the capacity be x.

Then 6+(3/4)x = (9/10)x
=> (9/10-3/4)x = 6
=> (36-30)x/40 = 6
=> 6x/40 = 6
=> x = 40 gallons.

:)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members
Location: New York, NY
Thanked: 13060 times
GMAT Score:790

by GMATGuruNY » Wed Aug 01, 2012 5:08 pm
grandh01 wrote:11. If 6 gallons of gasoline are added to a tank that is already filled to 3/4 of its
capacity, the tank is then filled to 9/10 of its capacity. How many gallons does
the tank hold?
(A) 20
(B) 24
(C) 36
(D) 40
(E) 60

Thanks in advance
We can plug in the answers, which represent the capacity of the tank.
The capacity is almost certainly a multiple of the two denominators in the problem (4 and 10).
Thus, the correct answer is likely to be A, D or E.
We should start with the middle value.

Answer choice D: 40 gallons
Adding 6 gallons to 3/4 of this value, we get:
6 + (3/4)40 = 36.
Volume/capacity = 36/40 = 9/10.
Succcess!

The correct answer is D.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 130
Joined: Fri Apr 20, 2012 8:13 amFollowed by: 4 members
Location: Toronto, Ontario
Thanked: 16 times
GMAT Score:650

by tisrar02 » Wed Aug 01, 2012 5:18 pm
A non algebraic way to think this problem through can be as follows:

The tank is already 3/4 or 75% full

Add 6 gallons and you get a total capacity of 9/10 or 90%.

90-75=15% is what 6 gallons represents in the tank

We know that 15X6=90% so 6x6=36.

We need 100% though, not 90% so it would be slightly larger than 36 hence 40 would be the correct answer.

NOTE: You only want to do this approach when the numbers are somewhat spread apart.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1