Find all School-related info fast with the new School-Specific MBA Forum

It is currently 02 Sep 2014, 23:33

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

GRE Weekly Challenge #5

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Senior Manager
Senior Manager
User avatar
Joined: 25 Jul 2011
Posts: 298
Location: India
Concentration: Operations, Strategy
GMAT 1: 730 Q50 V40
GPA: 3
WE: Operations (Non-Profit and Government)
Followers: 27

Kudos [?]: 134 [0], given: 286

GMAT ToolKit User GMAT Tests User Premium Member
GRE Weekly Challenge #5 [#permalink] New post 02 Oct 2011, 10:07
GMAT Club invites you to test your GRE knowledge for a chance to win! Each week, we will post a new Challenge Problem for you to attempt. If you submit the correct answer, you will be entered into that week’s drawing for a free Manhattan GRE Strategy guide. What are you waiting for? Get out your scrap paper and start solving! Click here to view contest & prize details


This week's question:
Cape Cod Cookies makes cookies of identical size from batches of cookie dough weighing 600 ounces. Cape Cod Cookies decides to modify the recipe by decreasing the weight of each cookie by 1 ounce. If Cape Cod Cookies discovers that it is now able to make 30 more cookies using the same batch of dough weighing 600 ounces, how much did each cookie originally weigh?
A.) 2
B.) 3
C.) 4
D.) 5
E.) 6

Please post your answer, along with the explanation, below. Get cracking! :)

Edit: This challenge is now closed

Solution
Let’s use x for the number of cookies produced by the original recipe, and y for the weight of each of the cookies. Given those variables, our first equation is simply xy = 600. We also need to create an equation that represents the new recipe. Since the number of cookies produced has increased by 30, and the weight of each cookie has decreased by 1, the new equation is (x + 30)(y – 1) = 600. Remember, the total weight is still 600 ounces. Foiling this equation yields xy – x + 30y – 30 = 600.
We now have two equations with two variables. There are several different paths we can go down here, but all involve substitution of one of the variables, and all will yield a quadratic. The simplest path is to recognize that since xy = 600, we can substitute for xy in the second equation to get 600 – x + 30y – 30 = 600. Subtracting the 600 from both sides, and adding an x to each side gives us 30y – 30 = x. We can now substitute for x in the first equation.
xy = 600 → y(30y – 30) = 600. This gives us 30y2 – 30y = 600.
Next divide both sides by 30 and set the equation to zero: y2 – y – 20 = 0.
Now that the equation is set to zero, we can factor it into its roots: (y + 4)(y – 5) = 0
The weight of the original cookies was thus 5 ounces, or -4 ounces. The negative root is a nonsensical result given the constraints of the problem, so the answer is 5 ounces.
An alternate solution would be to start with each answer choice, and see which satisfies the conditions of the problem. To implement this method, it’s helpful to set up a chart.
Image
From the chart we can see that only in answer D will we end up with 30 additional cookies after changing the recipe.
The correct answer is D.

The winner of this Week's Challenge is... (drum roll).... pitpit. Congratulations! Please send me a pm with your shipping address, and choice of Manhattan GRE Guide


Details of next week's competition will be posted in the Weekly Challenge Master thread... Stay tuned!
_________________

Net Impact's BUSINESS AS UNUSUAL Guide - a must-read!

Get the best GMAT Prep Resources with GMAT Club Premium Membership


Last edited by rasta on 05 Oct 2011, 08:59, edited 1 time in total.
Posted Winner & Solution
Kaplan Promo CodeKnewton GMAT Discount CodesManhattan GMAT Discount Codes
Manager
Manager
avatar
Joined: 03 Mar 2011
Posts: 94
Location: United States
Schools: Erasmus (S)
GMAT 1: 730 Q51 V37
GPA: 3.9
Followers: 1

Kudos [?]: 89 [0], given: 12

GMAT Tests User
Re: GRE Weekly Challenge #5 [#permalink] New post 03 Oct 2011, 10:37
This reply is hidden until the winner is announced.
_________________

If my post is useful for you not be ashamed to KUDO me!
Let kudo each other!

Manager
Manager
User avatar
Status: Still Struggling
Joined: 02 Nov 2010
Posts: 139
Location: India
GMAT Date: 10-15-2011
GPA: 3.71
WE: Information Technology (Computer Software)
Followers: 5

Kudos [?]: 13 [0], given: 8

Re: GRE Weekly Challenge #5 [#permalink] New post 03 Oct 2011, 11:51
This reply is hidden until the winner is announced.
_________________

Appreciation in KUDOS please!
Knewton Free Test 10/03 - 710 (49/37)
Princeton Free Test 10/08 - 610 (44/31)
Kaplan Test 1- 10/10 - 630
Veritas Prep- 10/11 - 630 (42/37)
MGMAT 1 - 10/12 - 680 (45/34)

Manager
Manager
avatar
Joined: 12 Aug 2011
Posts: 95
Location: United States (SC)
Concentration: Operations, General Management
Schools: Cornell (Johnson) - Class of 2014
GMAT 1: 710 Q48 V39
Followers: 0

Kudos [?]: 15 [0], given: 1

Re: GRE Weekly Challenge #5 [#permalink] New post 03 Oct 2011, 13:06
This reply is hidden until the winner is announced.
Intern
Intern
avatar
Joined: 25 Aug 2011
Posts: 6
Followers: 0

Kudos [?]: 1 [0], given: 0

Re: GRE Weekly Challenge #5 [#permalink] New post 03 Oct 2011, 15:20
This reply is hidden until the winner is announced.
Manager
Manager
avatar
Joined: 24 Nov 2010
Posts: 212
Location: United States (CA)
Concentration: Technology, Entrepreneurship
Schools: Ross '15, Duke '15
Followers: 2

Kudos [?]: 32 [0], given: 7

GMAT ToolKit User GMAT Tests User
Re: GRE Weekly Challenge #5 [#permalink] New post 03 Oct 2011, 18:51
This reply is hidden until the winner is announced.
Manager
Manager
User avatar
Status: Back to (GMAT) Times Square!!!
Joined: 15 Aug 2011
Posts: 189
Location: United States (IL)
GMAT 1: 650 Q49 V30
WE: Information Technology (Computer Software)
Followers: 1

Kudos [?]: 27 [0], given: 25

GMAT Tests User Reviews Badge
Re: GRE Weekly Challenge #5 [#permalink] New post 04 Oct 2011, 00:52
This reply is hidden until the winner is announced.
_________________

Working towards a goal...
V.

Intern
Intern
avatar
Joined: 04 Oct 2011
Posts: 1
Followers: 0

Kudos [?]: 0 [0], given: 0

Re: GRE Weekly Challenge #5 [#permalink] New post 04 Oct 2011, 13:30
This reply is hidden until the winner is announced.
Re: GRE Weekly Challenge #5   [#permalink] 04 Oct 2011, 13:30
    Similar topics Author Replies Last post
Similar
Topics:
GRE Weekly Challenge #4 rasta 6 23 Sep 2011, 02:52
1 GRE Weekly Challenge #3 rasta 9 14 Sep 2011, 20:57
1 Experts publish their posts in the topic GRE Weekly Challenge #2 rasta 7 01 Sep 2011, 00:10
2 GRE Weekly Challenge #1 rasta 14 23 Aug 2011, 09:42
1 GRE Weekly Challenge Showdown rasta 13 23 Aug 2011, 08:51
Display posts from previous: Sort by

GRE Weekly Challenge #5

  Question banks Downloads My Bookmarks Reviews Important topics  


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

Powered by phpBB © phpBB Group and phpBB SEO

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®.