Live GMAT classes with Target Test Prep start Nov 21 and Nov 22. First class free.

See classes
Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

Newsweek Readers’ Choice Awards 2026 winner: Target Test Prep, #1 Test Prep

Target Test Prep was voted #1 Best Test Prep in the 2026 Newsweek Readers’ Choice™ Awards.

★★★★★5.0563 reviews
GMATLiveTeachStarts Nov 22
Josh Braslow, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Josh Braslow, 20+ years in test prep

Nov 22 · Josh Braslow
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes + 6 months of TTP OnDemand
  • Attend the first class for free
  • Every class is recorded, so you never fall behind
View classes & enroll
Limited seats availableTarget Test Prep
EALiveTeachOnDemandStart anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

EXECUTIVE ASSESSMENT

with

165+ EA score guarantee
$05-day trial no automatic billing
Schedule
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll Start free 5-day trial
Limited cohort · enrollment openTrial includes full course accessTarget Test Prep
GMATOnDemandStart anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 563 reviewsTarget Test Prep

Weight average

Expert replies
Post new topic Post Reply
Subscribe topic
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 68
Joined: Wed Nov 30, 2011 3:12 pm
by bobdylan » Tue Jun 12, 2012 4:34 am
Each of the 30 boxes in a certain shipment weighs either 10 pound or 20 pounds, and the arithmetic mean of the boxes in the shipment is 18 pounds. If the average weight of the boxes is to be reduced to 14 pounds by removing some of the 20-pound boxes, how many 20-pound boxes must be removed?
a. 4 b. 6
c. 10
d. 20
e. 24
Top
Join the discussion
Source: — Problem Solving |
Legendary Member
Posts: 1159
Joined: Wed Apr 16, 2008 10:35 pm
Thanked: 56 times

by raunekk » Tue Jun 12, 2012 5:13 am
IMO : D = 20

a = 10 pound boxes
b = 20 pound boxes

a+b = 30 --- (1)
10(a) +20 (b) = 30* 18 ( given)

10a + 20 b = 540 --(2)

Solving 1 & 2, a= 6, b = 24

To reduce average to 14 by removing some 20 pound boxes

We use equation (2) to form new equation for average 14

10(6) + 20 (24-x) = 14 (30-x) ( Where x is the number of 20 pound boxes to be removed)

Solving, we get x = 20 (D)

Hope this helps!
Top
Join the discussion
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 » Tue Jun 12, 2012 6:36 am
bobdylan wrote:Each of the 30 boxes in a certain shipment weighs either 10 pound or 20 pounds, and the arithmetic mean of the boxes in the shipment is 18 pounds. If the average weight of the boxes is to be reduced to 14 pounds by removing some of the 20-pound boxes, how many 20-pound boxes must be removed?
a. 4
b. 6
c. 10
d. 20
e. 24
Total current weight = number*average = 30*18 = 540.
We can plug in the answers, which represent the number of 20-pound boxes that must be removed to reduce the average weight to 14.

Answer choice C: 10 of the 20-pound boxes
New total weight = 540 - 10*20 = 340.
New average for the 20 remaining boxes = 340/20 = 17.
To reduce the average weight further, more 20-pound boxes must be removed.
Eliminate A, B and C.

Answer choice D: 20 of the 20-pound boxes
New total weight = 540 - 20*20 = 140.
New average for the 10 remaining boxes = 140/10 = 14.
Success!

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