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

Combination problem

Expert replies
Post new topic Post Reply
Subscribe topic
Previous Topic Next Topic
Newbie | Next Rank: 10 Posts
Posts: 5
Joined: Tue Jan 23, 2007 6:58 pm
Thanked: 1 times
by takegmat » Thu Feb 22, 2007 8:01 pm
Can someone please solve this problem for me. This question is from the GMATPrep CAT exam.
You do not have the required permissions to view the files attached to this post.
Top
Join the discussion
Source: — Problem Solving |
User avatar
Community Manager
Posts: 789
Joined: Sun Jan 28, 2007 3:51 pmFollowed by: 1 member
Location: Silicon valley, California
Thanked: 30 times

by jayhawk2001 » Thu Feb 22, 2007 10:14 pm
Max number of 4 letter stocks = 26 * 26 * 26 * 26 = 26^4

Max number of 5 letter stocks = 26^5

Hence max number of 4 or 5 letter stocks = 26^4 + 26^5 = 27*(26^4)
which is option C
Top
Join the discussion

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 2228
Joined: Wed Dec 27, 2006 3:28 pmFollowed by: 694 members
Location: Montreal, Canada
Thanked: 639 times
GMAT Score:780

by Stacey Koprince » Mon Feb 26, 2007 11:04 pm
Just wanted to spell out jayhawk's last step a little further:

26^4 + 26^5 = 26^4(1 + 26) = 27*(26^4)
(so, you're pulling out the common term, 26^4, to simplify)
Please note: I do not use the Private Messaging system! I will not see any PMs that you send to me!!

Stacey Koprince
GMAT Instructor
Director of Online Community
Manhattan GMAT

Contributor to Beat The GMAT!

Learn more about me
Top
Join the discussion
User avatar
Master | Next Rank: 500 Posts
Posts: 400
Joined: Sat Mar 10, 2007 4:04 amFollowed by: 1 member
Thanked: 1 times

by f2001290 » Mon May 28, 2007 3:33 am
Jay

Could you please help me with this prob. question?

No of 4 letter words = 26C4*4!
No of 5 letter words = 26c5 * 5!

Total no of words = 26c4*4! + 26C5*5!

What is wrong with this? Probability is a pain..
Top
Join the discussion
Master | Next Rank: 500 Posts
Posts: 418
Joined: Mon Feb 26, 2007 6:41 pm
Thanked: 24 times

by Prasanna » Mon May 28, 2007 5:15 am
f2001290 wrote:Jay

Could you please help me with this prob. question?

No of 4 letter words = 26C4*4!
No of 5 letter words = 26c5 * 5!

Total no of words = 26c4*4! + 26C5*5!

What is wrong with this? Probability is a pain..
I agree with f2001290. The question has confused me. I was trying to solve it through Permutation :shock:
Top
Join the discussion
User avatar
Master | Next Rank: 500 Posts
Posts: 400
Joined: Sat Mar 10, 2007 4:04 amFollowed by: 1 member
Thanked: 1 times

by f2001290 » Mon May 28, 2007 6:25 am
I got the mistake with my approach.

If a 4 letter code is AAAA. 26C4*4! doesn't take this in to consideration.

Similar is the case with 5 letter words.
Top
Join the discussion
User avatar
Community Manager
Posts: 789
Joined: Sun Jan 28, 2007 3:51 pmFollowed by: 1 member
Location: Silicon valley, California
Thanked: 30 times

by jayhawk2001 » Mon May 28, 2007 8:10 am
f2001290 wrote:I got the mistake with my approach.

If a 4 letter code is AAAA. 26C4*4! doesn't take this in to consideration.

Similar is the case with 5 letter words.
Yes. Just to clarify,

choices for choosing 1st alphabet = 26
choices for choosing 2nd alphabet = 26
...etc

If you are doing 26C4, you are essentially excluding the alphabet that
you picked first for the 2nd, 3rd and 4th position.
Top
Join the discussion