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

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Director
Joined: 17 Oct 2005
Posts: 878
At a certain bakery, each roll costs r cents and each  [#permalink]

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18 Dec 2005, 17:08
1
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Difficulty:

25% (medium)

Question Stats:

76% (01:22) correct 24% (01:19) wrong based on 297 sessions

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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
Intern
Joined: 18 Nov 2005
Posts: 8
Re: At a certain bakery, each roll costs r cents and each  [#permalink]

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18 Dec 2005, 17:11
1
This is a typical GMAT trap. YOu might have seen my earlier post about picking numbers for DS. In general, two equations in two unknowns can be solved to get a unique (one) solution except when the two equations are the same. If you divide the information in statement 2, you get statemetn 1. So, statemetn 2 is not giving you any new information. Hence, the answer should be E.

-Srinivas (mathguru).
Director
Joined: 17 Oct 2005
Posts: 878
Re: At a certain bakery, each roll costs r cents and each  [#permalink]

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18 Dec 2005, 18:28
1
The oa is E

thanks srinivasssrk, i fell for it.
VP
Joined: 06 Jun 2004
Posts: 1008
Location: CA
Re: At a certain bakery, each roll costs r cents and each  [#permalink]

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18 Dec 2005, 19:28

(1) and (2) are the same thing
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Don't be afraid to take a flying leap of faith.. If you risk nothing, than you gain nothing...

Intern
Joined: 16 Oct 2005
Posts: 27
Re: At a certain bakery, each roll costs r cents and each  [#permalink]

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18 Dec 2005, 19:35
TeHCM wrote:

(1) and (2) are the same thing

For once, I get the right answer..
Senior Manager
Joined: 14 Apr 2005
Posts: 404
Location: India, Chennai
Re: At a certain bakery, each roll costs r cents and each  [#permalink]

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19 Dec 2005, 00:51
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.
Senior Manager
Joined: 05 Oct 2005
Posts: 473
Re: At a certain bakery, each roll costs r cents and each  [#permalink]

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19 Dec 2005, 10:44
Similar Equations , hence 1 equation , 2 variables .... E
Math Expert
Joined: 02 Sep 2009
Posts: 51100
Re: At a certain bakery, each roll costs r cents and each  [#permalink]

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05 Jan 2015, 03:12
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
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Manager
Joined: 24 May 2014
Posts: 87
Location: India
GMAT 1: 590 Q39 V32
GRE 1: Q159 V151

GRE 2: Q159 V153
GPA: 2.9
Re: At a certain bakery, each roll costs r cents and each  [#permalink]

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06 Sep 2016, 22:44
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: 641
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  [#permalink]

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08 Feb 2017, 20:26
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.
_________________

Thanks & Regards,
Anaira Mitch

Senior Manager
Joined: 08 Dec 2015
Posts: 293
GMAT 1: 600 Q44 V27
Re: At a certain bakery, each roll costs r cents and each  [#permalink]

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13 Feb 2017, 11:02
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.
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Joined: 09 Sep 2013
Posts: 9116
Re: At a certain bakery, each roll costs r cents and each  [#permalink]

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01 Jul 2018, 21:36
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).

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Re: At a certain bakery, each roll costs r cents and each &nbs [#permalink] 01 Jul 2018, 21:36
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