GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 24 Mar 2019, 16:37

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

Three different numbers have a product that is greater than

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

 
GMATH Teacher
User avatar
G
Status: GMATH founder
Joined: 12 Oct 2010
Posts: 911
Three different numbers have a product that is greater than  [#permalink]

Show Tags

New post 20 Feb 2019, 07:11
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

45% (02:06) correct 55% (01:27) wrong based on 33 sessions

HideShow timer Statistics

GMATH practice exercise (Quant Class 16)

The product of three different numbers is greater than 1000. What is the value of the largest among them?

(1) The numbers are primes.
(2) The product of the numbers is less than 1310.

_________________
Fabio Skilnik :: GMATH method creator (Math for the GMAT)
Our high-level "quant" preparation starts here: https://gmath.net
examPAL Representative
User avatar
G
Joined: 07 Dec 2017
Posts: 912
Re: Three different numbers have a product that is greater than  [#permalink]

Show Tags

New post 20 Feb 2019, 07:19
1) and 2) are clearly insufficient: there are endless possible results.
Let's try combined: we'll make a short list of prime numbers, starting with the lowest, and see if we can find more than one trio whse product is between 1000 and 1310:
2, 3, 5, 7, 9, 11, 13, 17...
the product of 9*11*13 is 99*13 - definitely in the range (even without calculating).
can we change this at all?
if we replace 13 with the next largest prime (17), it's too large: 99*17>1300
if we replace 9 with the next smallest (7): 77*13 = 770+210+21=980+21=1001 - in the range!
two possible solutions, not sufficient!
answer E
_________________
GMATH Teacher
User avatar
G
Status: GMATH founder
Joined: 12 Oct 2010
Posts: 911
Re: Three different numbers have a product that is greater than  [#permalink]

Show Tags

New post 20 Feb 2019, 11:50
fskilnik wrote:
GMATH practice exercise (Quant Class 16)

The product of three different numbers is greater than 1000. What is the value of the largest among them?

(1) The numbers are primes.
(2) The product of the numbers is less than 1310.

\(a < b < c\)

\(abc > 1000\)

\(? = c\)

\(\left( 1 \right)\,\,{\rm{primes}}\,\,\,\left\{ \matrix{
\,{\rm{Take}}\,\,\left( {a,b,c} \right) = \left( {7,11,13} \right)\,\,\,\,\left[ {abc = 1001} \right]\,\,\,\,\, \Rightarrow \,\,\,? = 13 \hfill \cr
\,{\rm{Take}}\,\,\left( {a,b,c} \right) = \left( {7,11,17} \right)\,\,\,\,\, \Rightarrow \,\,\,\,\,? = 17 \hfill \cr} \right.\)

\(\left( 2 \right)\,\,abc < 1310\,\,\,\,\,\,\left\{ \matrix{
\,\left( {{\mathop{\rm Re}\nolimits} } \right){\rm{Take}}\,\,\left( {a,b,c} \right) = \left( {7,11,13} \right)\,\,\,\, \Rightarrow \,\,\,? = 13 \hfill \cr
\,\left( {{\mathop{\rm Re}\nolimits} } \right){\rm{Take}}\,\,\left( {a,b,c} \right) = \left( {7,11,17} \right)\,\,\,\,\left[ {abc = 1309} \right]\,\,\,\,\, \Rightarrow \,\,\,? = 17 \hfill \cr} \right.\,\,\,\,\,\,\, \Rightarrow \,\,\,\,\,\,\,\left( {\rm{E}} \right)\)


We follow the notations and rationale taught in the GMATH method.

Regards,
Fabio.
_________________
Fabio Skilnik :: GMATH method creator (Math for the GMAT)
Our high-level "quant" preparation starts here: https://gmath.net
GMAT Tutor
avatar
S
Joined: 24 Jun 2008
Posts: 1395
Re: Three different numbers have a product that is greater than  [#permalink]

Show Tags

New post 20 Feb 2019, 16:35
DavidTutorexamPAL wrote:
Let's try combined: we'll make a short list of prime numbers, starting with the lowest, and see if we can find more than one trio whse product is between 1000 and 1310:
2, 3, 5, 7, 9, 11, 13, 17...
the product of 9*11*13 is 99*13 - definitely in the range (even without calculating).


9 is not a prime number.
_________________
GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com
GMAT Tutor
avatar
S
Joined: 24 Jun 2008
Posts: 1395
Re: Three different numbers have a product that is greater than  [#permalink]

Show Tags

New post 20 Feb 2019, 16:39
To make calculation easy here, you can set two of the primes to 2 and 5. Then we'll know the information is not sufficient if we can find at least two different prime numbers between 100 and 131. And there are a few primes in that range (101 and 103, for example).
_________________
GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com
GMAT Club Bot
Re: Three different numbers have a product that is greater than   [#permalink] 20 Feb 2019, 16:39
Display posts from previous: Sort by

Three different numbers have a product that is greater than

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.