At a bakery, all donuts are priced equally and all bagels : GMAT Data Sufficiency (DS)
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# At a bakery, all donuts are priced equally and all bagels

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At a bakery, all donuts are priced equally and all bagels [#permalink]

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06 Dec 2012, 03:17
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At a bakery, all donuts are priced equally and all bagels are priced equally. What is the total price of 5 donuts and 3 bagels at the bakery?

(1) At the bakery, the total price of 10 donuts and 6 bagels is $12.90. (2) At the bakery, the price of a donut is$0.15 less than the price of a bagel.
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Re: At a bakery, all donuts are priced equally and all bagels [#permalink]

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06 Dec 2012, 03:22
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At a bakery, all donuts are priced equally and all bagels are priced equally. What is the total price of 5 donuts and 3 bagels at the bakery?

Say the price of a donut is $x and the price of a bagel is$y. We need to find the value of 5x+3y.

(1) At the bakery, the total price of 10 donuts and 6 bagels is $12.90 --> given that 10x+6y=$12.9 --> reduce by 2: 5x+3y=$12.9/2. Sufficient. (2) At the bakery, the price of a donut is$0.15 less than the price of a bagel --> given that x=y-0.15 --> 5x+3y=5(y-0.15)+3y. We need the value of y (or x). Not sufficient.

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06 Dec 2012, 03:23
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Question asks for value of 5D + 3B.

1)10D + 6B = 12.9
5D + 3B = 12.9/2. Sufficient

2)We only have D = B - 0.15. Even after substitution of this in 5D + 3B we still have an unknown. Insufficient.

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Re: At a bakery, all donuts are priced equally and all bagels [#permalink]

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11 Oct 2016, 15:50
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At a bakery, all donuts are priced equally and all bagels are priced equally. What is the total price of 5 donuts and 3 bagels at the bakery?

(1) At the bakery, the total price of 10 donuts and 6 bagels is $12.90. (2) At the bakery, the price of a donut is$0.15 less than the price of a bagel.

We are given that all donuts are priced equally and all bagels are priced equally and need to determine the total price of 5 donuts and 3 bagels. Let’s start by defining some variables.

D = the price per donut

B = the price per bagel

Thus we need to determine: 5D + 3B = ?

Statement One Alone:

At the bakery, the total price of 10 donuts and 6 bagels is $12.90. Using the information in statement one, we can create the following equation: 10D + 6B = 12.90 We can simplify the equation by dividing the entire equation by 2. 5D + 3B = 6.45 Thus, the price for 5 donuts and 3 bagels is$6.45. Statement one alone is sufficient to answer the question. We can eliminate answer choices B, C, and E.

Statement Two Alone:

(2) At the bakery, the price of a donut is $0.15 less than the price of a bagel. I understand 1) is sufficient. But I'm not understanding why 2) is insufficient. If you let price of donut be x, then price of bagel is x+0.15. Therefore 10x + 6(x + 0.15) = 12.90. Solve that and get a value for x and obviously x + 0.15. Am I missing something obvious? Merging similar topics. Please refer to the discussion above. All OG 13 questions with solutions are here: the-official-guide-quantitative-question-directory-143450.html P.S. Please read carefully and follow: rules-for-posting-please-read-this-before-posting-133935.html Pay attention to rules 1, 3, and 7. Thank you. _________________ GMAT Club Legend Joined: 09 Sep 2013 Posts: 13534 Followers: 577 Kudos [?]: 163 [0], given: 0 Re: At a bakery, all donuts are priced equally and all bagels [#permalink] ### Show Tags 20 Jul 2015, 18:02 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). Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email. _________________ Intern Joined: 14 Sep 2015 Posts: 9 Followers: 0 Kudos [?]: 1 [0], given: 8 Re: At a bakery, all donuts are priced equally and all bagels [#permalink] ### Show Tags 19 Sep 2015, 13:49 I found the answer using both of the statements. 1) 10d + 5b = 12.90 2) d = b - 0.15 10(b-0.15)+6b=12.90 10b-1.5+6b=12.90 16b=14.4 b=0.9 [substitute for b in 2nd equation] d=0.9-0.15=0.75 5(0.75)+3(0.9)=6.45, which is equal to 12.90(0.5) GMAT Club Legend Joined: 09 Sep 2013 Posts: 13534 Followers: 577 Kudos [?]: 163 [0], given: 0 Re: At a bakery, all donuts are priced equally and all bagels [#permalink] ### Show Tags 10 Oct 2016, 09:54 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). Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email. _________________ Manager Joined: 11 Jul 2016 Posts: 86 Followers: 0 Kudos [?]: 10 [0], given: 83 Re: At a bakery, all donuts are priced equally and all bagels [#permalink] ### Show Tags 20 Nov 2016, 04:48 ScottTargetTestPrep wrote: Walkabout wrote: At a bakery, all donuts are priced equally and all bagels are priced equally. What is the total price of 5 donuts and 3 bagels at the bakery? (1) At the bakery, the total price of 10 donuts and 6 bagels is$12.90.
(2) At the bakery, the price of a donut is $0.15 less than the price of a bagel. We are given that all donuts are priced equally and all bagels are priced equally and need to determine the total price of 5 donuts and 3 bagels. Let’s start by defining some variables. D = the price per donut B = the price per bagel Thus we need to determine: 5D + 3B = ? Statement One Alone: At the bakery, the total price of 10 donuts and 6 bagels is$12.90.

Using the information in statement one, we can create the following equation:

10D + 6B = 12.90

We can simplify the equation by dividing the entire equation by 2.

5D + 3B = 6.45

Thus, the price for 5 donuts and 3 bagels is $6.45. Statement one alone is sufficient to answer the question. We can eliminate answer choices B, C, and E. Statement Two Alone: At the bakery, the price of a donut is$0.15 less than the price of a bagel.

We can express D in terms of B:

D = B - 0.15

Substituting B – 0.15 for D, we get:

5(B – 0.15) + 3B

5B – 0.75 + 3B

8B – 0.75

However, without knowing anything about the price of either D or B, or the total amount spent, we cannot determine the sum of 5D + 3B. Thus, statement two is insufficient.

While I do understand your explanation, I have a different viewpoint.

Its commonly known that if we have two unknowns , we need two equations to solve the Q.

In this Q, from(1) 10x +6y = 12.90
from (2) x = y - 0.15

If I see this, the first thing which comes to my mind is option C, ( 2 unknowns x, y and we can solve this with two equations)
How to negate this line of thought ?
Re: At a bakery, all donuts are priced equally and all bagels   [#permalink] 20 Nov 2016, 04:48
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