Last visit was: 14 Jul 2024, 23:00 It is currently 14 Jul 2024, 23:00
Toolkit
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

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.

# At a certain bakery, each roll costs r cents and each doughnut costs

SORT BY:
Tags:
Show Tags
Hide Tags
Director
Joined: 17 Oct 2005
Posts: 645
Own Kudos [?]: 1601 [52]
Given Kudos: 0
Intern
Joined: 18 Nov 2005
Posts: 3
Own Kudos [?]: 5 [5]
Given Kudos: 0
General Discussion
Director
Joined: 17 Oct 2005
Posts: 645
Own Kudos [?]: 1601 [1]
Given Kudos: 0
Senior Manager
Joined: 06 Jun 2004
Posts: 491
Own Kudos [?]: 1135 [2]
Given Kudos: 0
Location: CA
Re: At a certain bakery, each roll costs r cents and each doughnut costs [#permalink]
2
Kudos

(1) and (2) are the same thing
Intern
Joined: 16 Oct 2005
Posts: 11
Own Kudos [?]: 1 [1]
Given Kudos: 0
Re: At a certain bakery, each roll costs r cents and each doughnut costs [#permalink]
1
Kudos
TeHCM wrote:

(1) and (2) are the same thing

For once, I get the right answer..
Manager
Joined: 15 Apr 2005
Posts: 159
Own Kudos [?]: 32 [1]
Given Kudos: 0
Location: India, Chennai
Re: At a certain bakery, each roll costs r cents and each doughnut costs [#permalink]
1
Kudos
joemama142000 wrote:
At a certain bakery, each roll costs r cents and each doughnut costs d cents. If Alfredo bought rolls and doughnuts at the bakery, how many cents did he pay for each roll?

1) Alfredo paid $5.00 for 8 rolls and 6 doughnuts 2) Alfredo would have paid$ 10.00 if he had bought 16 rolls and 12 doughnuts

From stmt1 we get 8r+6d = 5
From stmt2 we get 16r + 12d = 10

Stmt1 * 2 = stmt 2, and we will not be able to solve this equen. So my answer is E.
Manager
Joined: 16 Aug 2011
Status:Bell the GMAT!!!
Affiliations: Aidha
Posts: 108
Own Kudos [?]: 196 [2]
Given Kudos: 43
Location: Singapore
Concentration: Finance, General Management
GMAT 1: 680 Q46 V37
GMAT 2: 620 Q49 V27
GMAT 3: 700 Q49 V36
WE:Other (Other)
Re: Marta bought several pencils. if each pencil was either 23 [#permalink]
2
Kudos
An interesting article at Karishma's (from Veritas) old blog to solve such equations:

https://gmatquant.blogspot.com/search?up ... -results=7

Hope it will help someone as it helped me
Math Expert
Joined: 02 Sep 2009
Posts: 94342
Own Kudos [?]: 640868 [2]
Given Kudos: 85011
Re: At a certain bakery, each roll costs r cents and each doughnut costs [#permalink]
1
Kudos
1
Bookmarks
At a certain bakery, each roll costs r cents and each doughnut costs d cents. If Alfredo bought rolls and doughnuts at the bakery, how many cents did he pay for each roll?

Let $$r$$ be the price of rolls in cents and $$d$$ be the price of doughnuts in cents. Note that $$r$$ and $$d$$ must be an integers. Q: $$r=?$$

(1) Alfredo paid $5.00 for 8 rolls and 6 doughnuts --> $$8r+6d=500$$ --> $$4r+3d=250$$. Multiple solutions are possible, for instance: $$r=25$$ and $$d=50$$ OR $$r=10$$ and $$d=70$$. Not sufficient. (2) Alfredo would have paid$ 10.00 if he had bought 16 rolls and 12 doughnuts --> $$16r+12d=1000$$ --> $$4r+3d=250$$. The same. Not sufficient.

(1)+(2) No new info. Not sufficient.

Check similar questions here: c-trap-questions-177044.html
Manager
Joined: 24 May 2014
Posts: 78
Own Kudos [?]: 23 [0]
Given Kudos: 990
Location: India
GMAT 1: 640 Q42 V35 (Online)
GRE 1: Q159 V151

GRE 2: Q159 V153
GPA: 2.9
Re: At a certain bakery, each roll costs r cents and each doughnut costs [#permalink]
Statement 1: 8r+6d=500 (Dollars to cents). Multiple values of r & d can work. For ex: r=10,d=70 & r=40, d=30. Not sufficient.
Statement 2: This is a tautological statement. (As St:1 is multiplied by 2).

Hence, option E.
Director
Joined: 26 Oct 2016
Posts: 506
Own Kudos [?]: 3409 [1]
Given Kudos: 877
Location: United States
Schools: HBS '19
GMAT 1: 770 Q51 V44
GPA: 4
WE:Education (Education)
Re: At a certain bakery, each roll costs r cents and each doughnut costs [#permalink]
1
Bookmarks
cost of each roll=r cents
cost of each doughnut=d cents

statement 1:

8r+6d=500

We have only one equation and 2 unknowns

Insufficient

statement 2:

16r+12d=1000
8r+6d=500( dividing by 2 throughout)

This is nothing but the same equation in statement 1..

Insufficient

Combining both the statements we have a single equation 8r+6d=500
and 2 unknowns...Hence the value of r cannot be determined

The ans is clearly E.
Senior Manager
Joined: 08 Dec 2015
Posts: 258
Own Kudos [?]: 118 [1]
Given Kudos: 36
GMAT 1: 600 Q44 V27
Re: At a certain bakery, each roll costs r cents and each doughnut costs [#permalink]
1
Kudos
Experts, is there a FAST way to detect if we are dealing with that situation (I don't remember the name) when we have 2 variables and it seems INSUF, but them there is only one combo of numbers that makes the equation possible, so it is SUF? How can we quickly check if that is the case? Here I was indecisive between D and E.
Director
Joined: 21 Feb 2017
Posts: 509
Own Kudos [?]: 1075 [0]
Given Kudos: 1091
Location: India
GMAT 1: 700 Q47 V39
Re: At a certain bakery, each roll costs r cents and each doughnut costs [#permalink]
iliavko wrote:
Experts, is there a FAST way to detect if we are dealing with that situation (I don't remember the name) when we have 2 variables and it seems INSUF, but them there is only one combo of numbers that makes the equation possible, so it is SUF? How can we quickly check if that is the case? Here I was indecisive between D and E.

VP
Joined: 14 Jul 2020
Posts: 1115
Own Kudos [?]: 1300 [0]
Given Kudos: 351
Location: India
Re: At a certain bakery, each roll costs r cents and each doughnut costs [#permalink]
At a certain bakery, each roll costs r cents and each doughnut costs d cents. If Alfredo bought rolls and doughnuts at the bakery, how many cents did he pay for each roll?

Stat1: Alfredo paid $5.00 for 8 rolls and 6 doughnuts It means, 8*r + 6*d = 500, or, 4*r + 3*d = 250, now, 4*r = 160 or 40 and 3*d= 90 or 210 respectively. Not sufficient. Stat2: Alfredo would have paid$ 10.00 if he had bought 16 rolls and 12 doughnuts
It means, 16*r + 12*d = 1000, or, 4*r + 3*d = 250. It is same like statement 1. Not sufficient.

Combining 1 and 2, Still we have 1 equation and 2 probable value of r. Not sufficient.

So, I think E.
Current Student
Joined: 24 Jan 2017
Posts: 146
Own Kudos [?]: 46 [0]
Given Kudos: 1120
Location: Brazil
Concentration: Entrepreneurship, Strategy
Schools: Fuqua '24 (A)
GPA: 3.2
WE:Consulting (Health Care)
Re: At a certain bakery, each roll costs r cents and each doughnut costs [#permalink]
Bunuel wrote:
At a certain bakery, each roll costs r cents and each doughnut costs d cents. If Alfredo bought rolls and doughnuts at the bakery, how many cents did he pay for each roll?

Let $$r$$ be the price of rolls in cents and $$d$$ be the price of doughnuts in cents. Note that $$r$$ and $$d$$ must be an integers. Q: $$r=?$$

(1) Alfredo paid $5.00 for 8 rolls and 6 doughnuts --> $$8r+6d=500$$ --> $$4r+3d=250$$. Multiple solutions are possible, for instance: $$r=25$$ and $$d=50$$ OR $$r=10$$ and $$d=70$$. Not sufficient. (2) Alfredo would have paid$ 10.00 if he had bought 16 rolls and 12 doughnuts --> $$16r+12d=1000$$ --> $$4r+3d=250$$. The same. Not sufficient.

(1)+(2) No new info. Not sufficient.

Check similar questions here: https://gmatclub.com/forum/c-trap-questions-177044.html

Bunuel GMATNinja (1) How did you come up with these solutions? (2) How to come up with solutions quickly? I'm taking too much time doing try & error...tks!
Manager
Joined: 12 Aug 2020
Posts: 52
Own Kudos [?]: 6 [0]
Given Kudos: 570
Re: At a certain bakery, each roll costs r cents and each doughnut costs [#permalink]
Bunuel Is there a fast way / formula to check if multiple solutions exist??? I know once you find the first solution, you can take the solution and add/subtract by the other number's multiplier to get additional solutions and check if they are in range. But what is the fastest way to either 1) get that first solution so that you can check if there are more, or 2) see there are multiple solutions possible? This seems to take more than 2 min
Manager
Joined: 30 May 2017
Posts: 94
Own Kudos [?]: 102 [1]
Given Kudos: 169
Location: India
Concentration: Finance, Strategy
GPA: 3.73
WE:Engineering (Consulting)
Re: At a certain bakery, each roll costs r cents and each doughnut costs [#permalink]
1
Kudos
testtakerstrategy wrote:
Bunuel Is there a fast way / formula to check if multiple solutions exist??? I know once you find the first solution, you can take the solution and add/subtract by the other number's multiplier to get additional solutions and check if they are in range. But what is the fastest way to either 1) get that first solution so that you can check if there are more, or 2) see there are multiple solutions possible? This seems to take more than 2 min

Not sure if I understood your query~, but I will say this!
For this kind of DS problem, you do not have to really solve it to know the answer. The first statement is giving you an equation which is like 8x+6y =5
Not sufficient as we do not have integer constraints for the price of the roll or doughnut.

Similarly . for second statement , the equation will be 16x + 12y = 10. Insufficient because of the same logic used in Statement 1.
Combining it,

If you observe the two equations are identical because if you multiply the first equation by 2, you will get the second statement's equation. Hence no additional information to solve. Hence answer is E
Manager
Joined: 05 Jul 2022
Posts: 108
Own Kudos [?]: 16 [0]
Given Kudos: 31
Location: India
Re: At a certain bakery, each roll costs r cents and each doughnut costs [#permalink]
This is a trap question. Both the equations are the same. Hence E

Although, don't choose E right away upon encountering two equations that are the same. Try to put values, if that equation has a unique solution then D would be your answer, and not C (that's another trap).

But here, we don't have a unique solution, hence choose E
Intern
Joined: 21 Sep 2023
Posts: 13
Own Kudos [?]: 0 [0]
Given Kudos: 39
GMAT 1: 610 Q47 V28
Re: At a certain bakery, each roll costs r cents and each doughnut costs [#permalink]
Bunuel wrote:
At a certain bakery, each roll costs r cents and each doughnut costs d cents. If Alfredo bought rolls and doughnuts at the bakery, how many cents did he pay for each roll?

Let $$r$$ be the price of rolls in cents and $$d$$ be the price of doughnuts in cents. Note that $$r$$ and $$d$$ must be an integers. Q: $$r=?$$

(1) Alfredo paid $5.00 for 8 rolls and 6 doughnuts --> $$8r+6d=500$$ --> $$4r+3d=250$$. Multiple solutions are possible, for instance: $$r=25$$ and $$d=50$$ OR $$r=10$$ and $$d=70$$. Not sufficient. (2) Alfredo would have paid$ 10.00 if he had bought 16 rolls and 12 doughnuts --> $$16r+12d=1000$$ --> $$4r+3d=250$$. The same. Not sufficient.

(1)+(2) No new info. Not sufficient.

Check similar questions here: https://gmatclub.com/forum/c-trap-questions-177044.html

Hi Bunuel, in a DS question if (1) and (2) provide the same information can we directly assume that the answer is E? Or are there any instances where it is C? Thank you for your reply !
Math Expert
Joined: 02 Sep 2009
Posts: 94342
Own Kudos [?]: 640868 [0]
Given Kudos: 85011
Re: At a certain bakery, each roll costs r cents and each doughnut costs [#permalink]
chloe2m wrote:
Bunuel wrote:
At a certain bakery, each roll costs r cents and each doughnut costs d cents. If Alfredo bought rolls and doughnuts at the bakery, how many cents did he pay for each roll?

Let $$r$$ be the price of rolls in cents and $$d$$ be the price of doughnuts in cents. Note that $$r$$ and $$d$$ must be an integers. Q: $$r=?$$

(1) Alfredo paid $5.00 for 8 rolls and 6 doughnuts --> $$8r+6d=500$$ --> $$4r+3d=250$$. Multiple solutions are possible, for instance: $$r=25$$ and $$d=50$$ OR $$r=10$$ and $$d=70$$. Not sufficient. (2) Alfredo would have paid$ 10.00 if he had bought 16 rolls and 12 doughnuts --> $$16r+12d=1000$$ --> $$4r+3d=250$$. The same. Not sufficient.

(1)+(2) No new info. Not sufficient.