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

It is currently 24 Mar 2019, 04:27

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

Molly went to a gift shop to buy some Christmas cards. Due to insuffic

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

Hide Tags

 
Manager
Manager
avatar
S
Joined: 18 Feb 2019
Posts: 150
Location: India
GMAT 1: 490 Q47 V13
GPA: 3.6
Molly went to a gift shop to buy some Christmas cards. Due to insuffic  [#permalink]

Show Tags

New post 28 Feb 2019, 07:47
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

72% (03:04) correct 28% (03:35) wrong based on 25 sessions

HideShow timer Statistics

Molly went to a gift shop to buy some Christmas cards. Due to insufficient money at that time, she decided to come back on the next day. The next day price per card was increased by $4 and she could buy 12 fewer cards than those she would have bought on the previous day for $135. What is the new price of each card? (Note: All the cards are equally priced).

A. 4
B. 5
C. 6
D. 9
E. 11
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7437
Re: Molly went to a gift shop to buy some Christmas cards. Due to insuffic  [#permalink]

Show Tags

New post 28 Feb 2019, 20:46
kiran120680 wrote:
Molly went to a gift shop to buy some Christmas cards. Due to insufficient money at that time, she decided to come back on the next day. The next day price per card was increased by $4 and she could buy 12 fewer cards than those she would have bought on the previous day for $135. What is the new price of each card? (Note: All the cards are equally priced).

A. 4
B. 5
C. 6
D. 9
E. 11



Various ways to do it..

(I) Use the choices..
A. 4... New price is 4, old price is 0... Not possible
B. 5... New price 5, old price 5-4=1.. Difference in cards = \(\frac{135}{1}-\frac{135}{5}=135-27\neq{12}\)
C. 6.. New price 6, old price 6-4=2.. Difference in cards = \(\frac{135}{2}-\frac{135}{6}\neq{12}\)
D. 9.. New price 9, old price 9-4=5.. Difference in cards = \(\frac{135}{5}-\frac{135}{9}=27-15=12\) YES
E. 11.. New price 11, old price 11-4=7.. Difference in cards = \(\frac{135}{7}-\frac{135}{11}\neq{12}\) Answer cannot be in fractions

(II) Algebraic
New price x and old price x-4..
\(\frac{135}{x-4}-\frac{135}{x}=135*\frac{x-x+4}{x(x-4)}=12.....135*4=12x^2-48x....x^2-4x-45=0.....(x-9)(x+5)=0\)
Hence x can be 9 or -5. Cannot be negative, so x=9

D
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html
4) Base while finding % increase and % decrease : https://gmatclub.com/forum/percentage-increase-decrease-what-should-be-the-denominator-287528.html


GMAT Expert

SVP
SVP
User avatar
P
Joined: 18 Aug 2017
Posts: 2454
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
GMAT ToolKit User Premium Member CAT Tests
Re: Molly went to a gift shop to buy some Christmas cards. Due to insuffic  [#permalink]

Show Tags

New post 03 Mar 2019, 03:59
let price of card be x $
so with 135$ , Molly could buy ; 135/x = y cards --(1)

now with 4$ increase she can buy y-12 cards
or say
135/x+4= y-12-(2)
solve 1 & 2
we ger
12x^2+48x-540=0
or say
x=-9, +5
x cannot be -ve
so initial price 5$ , new price ; 5+4 = 9 $
IMO D

kiran120680 wrote:
Molly went to a gift shop to buy some Christmas cards. Due to insufficient money at that time, she decided to come back on the next day. The next day price per card was increased by $4 and she could buy 12 fewer cards than those she would have bought on the previous day for $135. What is the new price of each card? (Note: All the cards are equally priced).

A. 4
B. 5
C. 6
D. 9
E. 11

_________________

If you liked my solution then please give Kudos. Kudos encourage active discussions.

GMAT Club Bot
Re: Molly went to a gift shop to buy some Christmas cards. Due to insuffic   [#permalink] 03 Mar 2019, 03:59
Display posts from previous: Sort by

Molly went to a gift shop to buy some Christmas cards. Due to insuffic

  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®.