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

It is currently 24 Apr 2019, 21:16

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

A jewel necklace contains only emeralds, rubies, and diamonds. If the

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

Hide Tags

 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 54496
A jewel necklace contains only emeralds, rubies, and diamonds. If the  [#permalink]

Show Tags

New post 16 Aug 2017, 01:56
1
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

75% (01:24) correct 25% (02:03) wrong based on 48 sessions

HideShow timer Statistics

A jewel necklace contains only emeralds, rubies, and diamonds. If the ratio of emeralds to diamonds is 2:7 and the ratio of diamonds to rubies is 3:2, then which of the following could not be the number of jewels on the necklace?

(A) 41

(B) 81

(C) 82

(D) 123

(E) 205

_________________
Manager
Manager
avatar
B
Joined: 21 Feb 2017
Posts: 73
GMAT ToolKit User
Re: A jewel necklace contains only emeralds, rubies, and diamonds. If the  [#permalink]

Show Tags

New post 16 Aug 2017, 02:00
1
B.
Rest all are multiple of 41 and ratio of e:d:r marble is 6:21:14. Add 6+21+14=41.


Sent from my XT1663 using GMAT Club Forum mobile app
Intern
Intern
User avatar
B
Joined: 28 May 2017
Posts: 18
Re: A jewel necklace contains only emeralds, rubies, and diamonds. If the  [#permalink]

Show Tags

New post 16 Aug 2017, 02:06
B -81 is the answer

Coz after simplifying
Emeralds : diamond : rubies

6 : 21: 14

So total 41 so every option that is divisible by 41 can be the no of jewels

So the only no not divisible by 41 is 81

So 81 is the answer B


Sent from my iPhone using GMAT Club Forum
Senior SC Moderator
avatar
V
Joined: 22 May 2016
Posts: 2653
A jewel necklace contains only emeralds, rubies, and diamonds. If the  [#permalink]

Show Tags

New post Updated on: 16 Aug 2017, 13:17
DOUBLE POST, SEE BELOW
_________________
Listen, are you breathing just a little, and calling it a life?
-- Mary Oliver



For practice SC questions with official explanations that were posted and moderated by the SC Team,
go to SC Butler here: https://gmatclub.com/forum/project-sc-butler-get-2-sc-questions-everyday-281043.html

Originally posted by generis on 16 Aug 2017, 13:06.
Last edited by generis on 16 Aug 2017, 13:17, edited 1 time in total.
Senior SC Moderator
avatar
V
Joined: 22 May 2016
Posts: 2653
Re: A jewel necklace contains only emeralds, rubies, and diamonds. If the  [#permalink]

Show Tags

New post 16 Aug 2017, 13:13
genxer123 wrote:
Bunuel wrote:
A jewel necklace contains only emeralds, rubies, and diamonds. If the ratio of emeralds to diamonds is 2:7 and the ratio of diamonds to rubies is 3:2, then which of the following could not be the number of jewels on the necklace?

(A) 41

(B) 81

(C) 82

(D) 123

(E) 205

Emeralds : Diamonds = 2:7 and
Diamonds : Rubies = 3:2

Before you can figure out how many total jewels might be on a necklace, you have to know the relationship among emeralds and diamonds and rubies.

But because the ratio number for diamonds doesn't match, you can't figure out that relationship until you make a common term.

The method is derivable, but maybe just writing it out will help.

There are two ratios that share a common element , diamonds. To find the combined relationship, find the equivalent of the least common multiple.

That is, figure out how to make diamonds equal in both ratios, and then you can combine ratios .

1. Write the ratios as you have them, putting the element they have in common in the middle

|__E__|__D__|__R__|
|__2__|__7__|-------|
|-------|__3__|__2__|

2. You need the Ds (diamonds) to be equal. Take the LCM of 3 and 7 = 21.

3. Then multiply each row by the number that will get you to D = 21: multiply both parts of the first row by 3, and both parts of the second row by 7

|__E__|__D__|__R__|---------------->|__E__|__D__|__R__|
|__2__|__7__|-------| ---- x 3------->|__6__|__21__|--------|
|-------|__3__|__2__| ---- x 7------->|--------|__21__|__14__|

The right hand chart shows the combined ratio where E: D: R = 6x: 21x: 14x

Total parts of combined ratio: 6x + 21x + 14x = 41x

So the answer has to be a multiple of 41.

81 is not a multiple of 41.

Answer B


P.S. If you're on a phone, turn it to landscape. Then the charts will line up. (Wow is it hard to make charts . . . .)
_________________
Listen, are you breathing just a little, and calling it a life?
-- Mary Oliver



For practice SC questions with official explanations that were posted and moderated by the SC Team,
go to SC Butler here: https://gmatclub.com/forum/project-sc-butler-get-2-sc-questions-everyday-281043.html
Senior PS Moderator
User avatar
V
Joined: 26 Feb 2016
Posts: 3386
Location: India
GPA: 3.12
Re: A jewel necklace contains only emeralds, rubies, and diamonds. If the  [#permalink]

Show Tags

New post 16 Aug 2017, 20:17
Let the emeralds in the necklace be represented by E,
the rubies in the necklace be represented by R and diamonds in the necklace by D.
Therefore,
E:D = 2x:7x
D:R = 3x:2x

Since we need to find a common ratio, we need to multiply the emerald, diamond ratio by a factor of 3 and the diamond, ruby ratio by a factor of 7.
E:D also equals 6x : 21x and D:R equals 21x : 14x
Hence, the common ratio is 6x : 21x : 14x.

Therefore, the total number of jewels in the necklace is a mutliple of 41(6x + 21x +14x = 41x)
Of the answer options(Only B, 81) is not a multiple of 41 and is our answer.
_________________
You've got what it takes, but it will take everything you've got
Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 10624
Re: A jewel necklace contains only emeralds, rubies, and diamonds. If the  [#permalink]

Show Tags

New post 22 Apr 2019, 03:04
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Club Bot
Re: A jewel necklace contains only emeralds, rubies, and diamonds. If the   [#permalink] 22 Apr 2019, 03:04
Display posts from previous: Sort by

A jewel necklace contains only emeralds, rubies, and diamonds. If the

  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®.