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 →

Problem Solving Question

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Newbie | Next Rank: 10 Posts
Posts: 4
Joined: Sun Jul 24, 2011 9:51 am
by amidoshi » Tue Aug 16, 2011 9:20 am
If the positive integer y is divisible by 3, 8, and 12, then which of the following must y be divisible by?

I. 24
II. 36
III. 48
I only
II only
I and II only
II and III only
I, II, and III

I understand the II cannot be an answer, but I don't understand what III cannot be included. 48 is divisible by 3, 8, and 12.

Please help!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
User avatar
Senior | Next Rank: 100 Posts
Posts: 64
Joined: Sun Jul 24, 2011 9:11 am
Thanked: 13 times
GMAT Score:610

by sumgb » Tue Aug 16, 2011 10:19 am
If y = 24. Is 24 divisible by 48? there's your answer...

hope this helps.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 312
Joined: Tue Aug 02, 2011 3:16 pmFollowed by: 33 members
Location: New York City
Thanked: 130 times
GMAT Score:780

by gmatboost » Wed Aug 17, 2011 2:14 pm
Sumgb gave a good answer to why 48 is not included

The thorough approach to the question:
3 = 3
8 = 2^3
12 = 2^2 * 3

To capture all of these the pieces we MUST have are 3*(2^3) = 24
Greg Michnikov, Founder of GMAT Boost

GMAT Boost offers 250+ challenging GMAT Math practice questions, each with a thorough video explanation, and 100+ GMAT Math video tips, each 90 seconds or less.
It's a total of 20+ hours of expert instruction for an introductory price of just $10.
View sample questions and tips without signing up, or sign up now for full access.

Also, check out the most useful GMAT Math blog on the internet here.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Newbie | Next Rank: 10 Posts
Posts: 4
Joined: Sun Jul 24, 2011 9:51 am

by amidoshi » Wed Aug 17, 2011 3:38 pm
So, because 48 has 4 instances of 2, it cannot be confirmed that y will be divisible by 48? Sumgb's answer confused me because 48 is divisible by 24 so I would assume that y would also be divisible by 48.

Or, is it that because 48 is already divisible by 24 we don't need to include it in the list?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 370
Joined: Sat Jun 11, 2011 8:50 pmFollowed by: 2 members
Location: Arlington, MA.
Thanked: 27 times

by winniethepooh » Wed Aug 17, 2011 7:53 pm
The question is asking you to find an answer which of the option must Y be divisible by?

The answer is simply the LCM of the three numbers(this answer alone satisfies the MUST criteria)
That is 24.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 312
Joined: Tue Aug 02, 2011 3:16 pmFollowed by: 33 members
Location: New York City
Thanked: 130 times
GMAT Score:780

by gmatboost » Wed Aug 17, 2011 8:38 pm
Amidoshi,

All we know is that Y must be divisible by 3, 8, and 12

That means it must be divisible by 3, 2^3, and 2^2 * 3
This in turn means it MUST be divisible by 3*(2^3)

Could it be divisible by 2^4? Maybe, but we don't know for sure. There is no reason it MUST be divisible by that.

The clearest example of this is 24, which meets all the conditions (divisible by 3, 8, and 12). So 24 could be Y. And 24 is NOT divisible by 48. This gives a numerical demonstration that while Y MIGHT be divisible by 24, there is no reason it MUST be.
Greg Michnikov, Founder of GMAT Boost

GMAT Boost offers 250+ challenging GMAT Math practice questions, each with a thorough video explanation, and 100+ GMAT Math video tips, each 90 seconds or less.
It's a total of 20+ hours of expert instruction for an introductory price of just $10.
View sample questions and tips without signing up, or sign up now for full access.

Also, check out the most useful GMAT Math blog on the internet here.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Newbie | Next Rank: 10 Posts
Posts: 9
Joined: Thu Aug 04, 2011 12:07 am

by krishna8143 » Wed Aug 17, 2011 10:24 pm
simple and common logic for all these type of problems is when the num. is divisable by some different numbers, it must divisible by L.C.M of those numbers

so as in this case lcm of 3,8,12 is 24

so the ans is 24
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1