Summer is Coming! Join the Game of Timers Competition to Win Epic Prizes. Registration is Open. Game starts Mon July 1st.

It is currently 20 Jul 2019, 00:37

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

During a sale, a store sells 20 percent of its remaining stock each

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

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 56300
During a sale, a store sells 20 percent of its remaining stock each  [#permalink]

Show Tags

New post 12 Dec 2015, 09:26
15
00:00
A
B
C
D
E

Difficulty:

  95% (hard)

Question Stats:

43% (02:32) correct 57% (02:30) wrong based on 237 sessions

HideShow timer Statistics


Most Helpful Community Reply
Senior Manager
Senior Manager
User avatar
B
Joined: 10 Mar 2013
Posts: 487
Location: Germany
Concentration: Finance, Entrepreneurship
Schools: WHU MBA"20 (A)
GMAT 1: 580 Q46 V24
GPA: 3.88
WE: Information Technology (Consulting)
GMAT ToolKit User
Re: During a sale, a store sells 20 percent of its remaining stock each  [#permalink]

Show Tags

New post 12 Dec 2015, 13:04
6
1
1
Bunuel wrote:
During a sale, a store sells 20 percent of its remaining stock each day, without replenishment. After four days, what fraction of its original stock has it sold?

A. 1/625
B. 256/625
C. 61/125
D. 64/125
E. 369/625



Let's pick a smart number for the initial amount. The store sold 20 percent each day, hmm, after looking at the answer choices 625 is used pretty often, so let's pick it.
1st day: 125 items sold, 500 left
2nd day: 100 items sold, 400 left
3rd day: 80 sold, 320 left
4th day: 64 sold, 256 left
\(Sum of the sold items = 125+100+80+64=369 --> \frac{369}{625}\), Answer E
_________________
When you’re up, your friends know who you are. When you’re down, you know who your friends are.

Share some Kudos, if my posts help you. Thank you !

800Score ONLY QUANT CAT1 51, CAT2 50, CAT3 50
GMAT PREP 670
MGMAT CAT 630
KAPLAN CAT 660
General Discussion
EMPOWERgmat Instructor
User avatar
V
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 14590
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: During a sale, a store sells 20 percent of its remaining stock each  [#permalink]

Show Tags

New post 14 Dec 2015, 17:07
Hi All,

This question can be solved by TESTing VALUES (the approach that BrainLab used). I'd like to add a particular point as to WHY it's so useful to use the number 625 - it's not just that it shows up in 3 of the 5 answer choices... ALL 5 answer choices can be written as 'fractions out of 625', it's just that 2 of the answers have been reduced.

Once you have that starting value, you can work through the individual calculations as shown. It's important to note what the question specifically ASKS FOR though. One of the wrong choices answers the question "what fraction of its stock does it have left?' (Answer B).

GMAT assassins aren't born, they're made,
Rich
_________________
760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

*****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!*****

Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save $75 + GMAT Club Tests Free
  Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/
Retired Moderator
avatar
P
Joined: 22 Aug 2013
Posts: 1435
Location: India
Re: During a sale, a store sells 20 percent of its remaining stock each  [#permalink]

Show Tags

New post 30 May 2017, 23:27
The store keeps selling 20% or 1/5 of its stock daily, without replacing. So at the end of the day, the stock that remains is 4/5 of the original stock. We have to find the fraction after four days, which means we have to multiply the original value four times by 4/5.

So lets start with a number '625' which represents the original stock. (because 625 = 5^4)
Thus, stock after 4 days = 625 * 4/5 * 4/5 * 4/5 * 4/5 = 256.
Stock remaining = 625-256 = 369

So the required fraction = 369/625

Hence E is answer
Target Test Prep Representative
User avatar
D
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 6968
Location: United States (CA)
Re: During a sale, a store sells 20 percent of its remaining stock each  [#permalink]

Show Tags

New post 01 Jun 2017, 10:23
1
Bunuel wrote:
During a sale, a store sells 20 percent of its remaining stock each day, without replenishment. After four days, what fraction of its original stock has it sold?

A. 1/625
B. 256/625
C. 61/125
D. 64/125
E. 369/625


We can let the initial stock = x.

After day 1:

0.2x is sold and 0.8x is left over.

After day 2:

0.2(0.8x) = 0.16x is sold and 0.8(0.8x) = 0.64x is left over.

After day 3:

(0.2)(0.64x) = 0.128x is sold and 0.8(0.64x) = 0.512x is left over.

After day 4:

0.2(0.512x) = 0.1024x is sold and 0.8(0.512x) = 0.4096x is left over.

Since 0.4096x is left over at the end of 4 days, 1 - 0.4096 = 0.5904, or 59.04%, of the initial stock was sold. We re-express 0.5904 as a fraction: 0.5904 = 5904/10,000 = 738/1250 = 369/625 of the original stock was sold.

Answer: E
_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Manager
Manager
User avatar
S
Status: Don't Give Up!
Joined: 15 Aug 2014
Posts: 96
Location: India
Concentration: Operations, General Management
GMAT Date: 04-25-2015
WE: Engineering (Manufacturing)
CAT Tests
Re: During a sale, a store sells 20 percent of its remaining stock each  [#permalink]

Show Tags

New post 03 Jun 2017, 07:24
Most easiest option i guess is use fraction i.e. first day 1/5 of X is sold and next day 4/5 of the stock remained.
_________________
- Sachin

-If you like my explanation then please click "Kudos"
Board of Directors
User avatar
P
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4512
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User
During a sale, a store sells 20 percent of its remaining stock each  [#permalink]

Show Tags

New post 03 Jun 2017, 08:42
1
Bunuel wrote:
During a sale, a store sells 20 percent of its remaining stock each day, without replenishment. After four days, what fraction of its original stock has it sold?

A. 1/625
B. 256/625
C. 61/125
D. 64/125
E. 369/625


\(20\) % = \(\frac{1}{5}\)

Thus, there is a reduction in stock by the fraction of \(\frac{1}{5}^{th}\)

Let, The total stock be 625 Units....

Day 1 : Stock in Hand = 625, Sold = 125, Remaining = 500
Day 2 : Stock in Hand = 500, Sold = 100, Remaining = 400
Day 3 : Stock in Hand = 400, Sold = 80, Remaining = 320
Day 4 : Stock in Hand = 320, Sold = 64, Remaining = 256

Total Quantity of Stock sold is 625 - 256 = 369 Units...

Quote:
After four days, what fraction of its original stock has it sold?


So, fraction of Original Stock he has is \(\frac{369}{625}\)

Thus, Answer must be (C) \(\frac{369}{625}\)
_________________
Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )
Intern
Intern
avatar
B
Joined: 11 Oct 2018
Posts: 21
Location: Germany
Re: During a sale, a store sells 20 percent of its remaining stock each  [#permalink]

Show Tags

New post 26 Jan 2019, 13:22
1
I guess the easiest approach is to subtract the remaining stock from the original:

\(1-(\frac{4}{5})^4\)
\(=\frac{625}{625}-\frac{256}{625}\)
\(=\frac{369}{625}\)
Intern
Intern
avatar
B
Joined: 15 Jul 2016
Posts: 10
Re: During a sale, a store sells 20 percent of its remaining stock each  [#permalink]

Show Tags

New post 25 Apr 2019, 17:42
I chose my smart number as 625. Why? because it's in answer choices.

In the end just build a quick calculation matrix of day/inventory/sold and work your way through 4 days. It took me less than 2 minutes to calculate.
GMAT Club Bot
Re: During a sale, a store sells 20 percent of its remaining stock each   [#permalink] 25 Apr 2019, 17:42
Display posts from previous: Sort by

During a sale, a store sells 20 percent of its remaining stock each

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





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