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 →

nth term question

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 2623
Joined: Mon Jun 02, 2008 3:17 amFollowed by: 355 members
Location: Montreal
Thanked: 1090 times
GMAT Score:780

by Ian Stewart » Thu Feb 04, 2010 2:28 pm
By substitution we find that

t_3 = 3/5
t_4 = 4/6
t_5 = 5/7
...
t_51 = 51/53
t_52 = 52/54
t_53 = 53/55

so when we multiply these, the result is

(3/5)(4/6)(5/7)(6/8) ... (51/53)(52/54)(53/55)

Notice that almost all of the numerators will cancel with the denominator of the term two earlier (so the numerator in 5/7 cancels with the denominator of 3/5, for example); after canceling, all we have left is

(3*4)/(54*55) = 2/(9*55) = 2/495
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

ianstewartgmat.com
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 25
Joined: Fri Jan 29, 2010 2:27 am
Thanked: 1 times

by neelimareddym » Thu Feb 04, 2010 10:20 pm
harsh.champ wrote:The question is in the attachment file.

The answer choices are
(1)2/495
(2)2/477
(3)12/55
(4)1/485
(5)1/2970
tn =n/(n+2)

=> t3=3/5
t4 = 4/6
t5=5/7
t6=6/8
...
...
...
t51 =51/53
t52=52/54
t53 = 53/55

Series = (3/5)*(4/6)*(5/7)*...*(51/53)*(52/54)*(53/55)
=(3*4)/(54*55)
=2/495
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 1560
Joined: Tue Nov 17, 2009 2:38 amFollowed by: 5 members
Thanked: 137 times

by thephoenix » Thu Feb 04, 2010 10:38 pm
t3=3/5
t4=4/6
t5=5/6

hence the pattern is
3/5*4/6*5/7...................51/53*52/54*53/55
the first two numerator and the last two denominator will left and all others will get cancel out

hence
3*4/54*55=2/495
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1