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

Permutation and Combination Problem, Need help

Expert replies
Post new topic Post Reply
Subscribe topic
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 172
Joined: Wed Oct 31, 2007 11:21 am
Thanked: 1 times
by gmattester » Wed Jul 30, 2008 11:54 am
A certain stock exchange designates each stock with a one-, two-, or three letter code, where each letter is selected from the 26 letters of the alphabet. if the letters may be repeated and if the same letters used in a different order constitute a different code, how many different stocks is it possible to uniquely designate these codes?

a) 2951
b) 8125
c) 15600
d) 16302
e) 18278

Can someone please explain how to solve this question.
Top
Join the discussion
Source: — Problem Solving |
Master | Next Rank: 500 Posts
Posts: 104
Joined: Wed Jun 04, 2008 4:04 pm
Thanked: 6 times

by swati.sug » Wed Jul 30, 2008 12:01 pm
If code is one letter
No of possible codes = 26

If code is two letters
No of possible codes = 26*26 =676

If code is three letters
No of possible codes = 26*26*26 =17576

Total = 26+676 +17576 =18278

Hope that helps!
Top
Join the discussion
Legendary Member
Posts: 1153
Joined: Wed Jun 20, 2007 6:21 amFollowed by: 2 members
Thanked: 146 times

by parallel_chase » Wed Jul 30, 2008 12:08 pm
Even I got 18278

26+676 +17576 =18278

Whats the OA?
Top
Join the discussion
Master | Next Rank: 500 Posts
Posts: 172
Joined: Wed Oct 31, 2007 11:21 am
Thanked: 1 times

Can you explain this

by gmattester » Wed Jul 30, 2008 12:12 pm
Thanks swati......
Answer is right.

Can you explain this. If we are looking for different stocks possible to uniquely designate these codes then

If code is one letter
No of possible codes should be 26

If code is two letters
No of possible codes should be 26*25= 650

If code is three letters
No of possible codes should be 26*25*24=15600

Total = 26+650 +15600
Top
Join the discussion
Master | Next Rank: 500 Posts
Posts: 118
Joined: Sun Jun 01, 2008 1:47 pmFollowed by: 1 member
Thanked: 5 times

by ricky » Wed Jul 30, 2008 12:51 pm
Since we can repeat a letter in the code, therefore for a two letter code the number of possibilities are 26* 26 and NOT 26*25.Same is true for a three letter code.
Top
Join the discussion