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

Redeem

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.

★★★★★5.0559 reviews
GMATLiveTeach Starts Oct 17
Chris Peckover, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Chris Peckover, 100th-Percentile GMAT Scorer

Oct 17 · Chris Peckover
Sat · 11:00 AM to 2:00 PM ET
Oct 20 · Chris Peckover
Tue, Thu · 8:00 to 10:00 PM ET
Oct 25 · Josh Braslow
Sun · 1:00 to 4:00 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
EALiveTeachOnDemand 5 seats left Start anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

165+ EA score guarantee
$05-day trial no automatic billing
Schedule
Sun · 9:30 AM to 12:30 PM ET
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
GMATOnDemand Start 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 559 reviewsTarget Test Prep

Compare the format, schedule, and included access before enrolling. Prices and seat counts shown reflect the supplied offer details.

A jewelry store sells customized rings

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 292
Joined: Fri Jul 17, 2009 8:39 amFollowed by: 1 member
Thanked: 6 times
by pnk » Sat Jul 24, 2010 11:10 am
A jewelry store sells customized rings in which 3 gems selected by the customer are set in a straight row along the band of the ring. If exactly 5 different gems are available and if at least 2 gems in any given ring must be different, how many different rings are possible?
20
60
90
120
210


OA - 120
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
User avatar
Legendary Member
Posts: 1893
Joined: Sun May 30, 2010 11:48 pmFollowed by: 7 members
Thanked: 215 times

by kvcpk » Sat Jul 24, 2010 11:17 am
pnk wrote:A jewelry store sells customized rings in which 3 gems selected by the customer are set in a straight row along the band of the ring. If exactly 5 different gems are available and if at least 2 gems in any given ring must be different, how many different rings are possible?
20
60
90
120
210


OA - 120
Number of rings when all 3 gems are different:
5*4*3=60

Number of rings when 2 gems are same and the other is different:
Number of rings with the 2 same gems in first 2 positions 5*1*4 = 20
Now, the positions can be changed 3c2 = 3 ways.
Hence 20*3 = 60 rings are possible.

Total =60+60 = 120
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 » Sat Jul 24, 2010 11:34 am
pnk wrote:A jewelry store sells customized rings in which 3 gems selected by the customer are set in a straight row along the band of the ring. If exactly 5 different gems are available and if at least 2 gems in any given ring must be different, how many different rings are possible?
20
60
90
120
210


OA - 120
Remember this rule:

good = total - bad

total = 5 * 5 * 5 = 125 (number of ways to arrange 3 gems from 5 choices if gems can be reused)

bad = 5 (a bad arrangement is all 3 gems the same; since we have 5 gems from which to choose, there are 5 ways to have all 3 gems be the same)

good = total - bad = 125 - 5 = 120.

An efficient approach that requires less messy arithmetic.
Last edited by GMATGuruNY on Sat Jul 24, 2010 11:37 am, edited 2 times in total.
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
Legendary Member
Posts: 1893
Joined: Sun May 30, 2010 11:48 pmFollowed by: 7 members
Thanked: 215 times

by kvcpk » Sat Jul 24, 2010 11:36 am
GMATGuruNY wrote:
pnk wrote:A jewelry store sells customized rings in which 3 gems selected by the customer are set in a straight row along the band of the ring. If exactly 5 different gems are available and if at least 2 gems in any given ring must be different, how many different rings are possible?
20
60
90
120
210


OA - 120
Remember this rule:

good = total - bad

total = 5 * 5 * 5 = 125 (number of ways to arrange 3 gems from the 5 choices if gems can be reused)

bad = 5 (a bad arrangement is all gems the same; since we have 5 gems from which to choose, there are 5 ways to have all 3 gems be the same)

good = total - bad = 125 - 5 = 120.

An efficient approach that requires less messy arithmetic.
Thats Awesome!!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Newbie | Next Rank: 10 Posts
Posts: 6
Joined: Sun Apr 11, 2010 6:21 am

by bendaniel » Sun Jul 25, 2010 7:47 am
Hi,
I'm not able to understand the concept of "total"....
how it is 5*5*5?... could somebody please explain this?... i, on the other hand assumed that to be 5!, which is 120....
Enlighten me please...
thank u.....
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 » Sun Jul 25, 2010 7:56 am
bendaniel wrote:Hi,
I'm not able to understand the concept of "total"....
how it is 5*5*5?... could somebody please explain this?... i, on the other hand assumed that to be 5!, which is 120....
Enlighten me please...
thank u.....
In the problem above, we are arranging 3 gems from 5 choices.

Total = total number of ways to arrange 3 gems from 5 choices if we can reuse gems. We have 5 choices for the 1st position, 5 choices for the 2nd position, 5 choices for the 3rd position: 5*5*5=125.

Bad = an arrangement in which all 3 gems are the same (because a good arrangement is one in which at least 2 gems are different). Since we have 5 gems to choose from, there are 5 ways to have the 3 gems all be the same. So bad = 5.

Good = Total - Bad = 125 - 5 = 120.

Does this help?
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
Newbie | Next Rank: 10 Posts
Posts: 6
Joined: Sun Apr 11, 2010 6:21 am

by bendaniel » Sun Jul 25, 2010 8:07 am
s it helps... thanq guru.... :)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 16
Joined: Sun Jan 30, 2011 6:34 amFollowed by: 1 member

by vishaljainsxc » Mon Sep 19, 2011 9:12 pm
Can you make me understand how


Bad = an arrangement in which all 3 gems are the same (because a good arrangement is one in which at least 2 gems are different). Since we have 5 gems to choose from, there are 5 ways to have the 3 gems all be the same. So bad = 5.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 627
Joined: Thu Jun 23, 2011 9:12 amFollowed by: 1 member
Thanked: 4 times

by mankey » Wed Sep 21, 2011 5:15 am
What is wrong with the following approach?

Selecting 2 different gems out of 5: 5C2 * 3!/2!=30
Selecting 3 different gems out of 5: 5C3 * 3!=60
Total=30+60=90

Please clarify.

Thanks
Mankey
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 Sep 21, 2011 6:45 am
vishaljainsxc wrote:Can you make me understand how


Bad = an arrangement in which all 3 gems are the same (because a good arrangement is one in which at least 2 gems are different). Since we have 5 gems to choose from, there are 5 ways to have the 3 gems all be the same. So bad = 5.
A bad arrangement is one in which all 3 gems are the same.
Number of options for the first gem = 5. (Any of the 5 gems can be chosen.)
Number of options for the second gem = 1. (Must be the same as the first gem.)
Number of options for the third gem = 1. (Must be the same as the first gem.)
To combine the options above, we multiply:
Bad arrangements = 5*1*1 = 5.
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
Junior | Next Rank: 30 Posts
Posts: 29
Joined: Tue Jul 12, 2011 1:07 pmFollowed by: 1 member
Thanked: 8 times

by beatthegmat.garry » Wed Sep 21, 2011 7:09 pm
Why do you consider permutations here?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1