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15 Oct 2012, 04:41
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Re: At a certain picnic, each of the guests was served either a [#permalink]
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15 Oct 2012, 04:41
SOLUTIONAt a certain picnic, each of the guests was served either a single scoop or a double scoop icecream. How many of the guests were served a double scoop of icecream?(1) At the picnic, 60 percent of the guests were served a double scoop of icecream > \(\frac{x}{y}=\frac{4}{6}=\frac{2}{3}\), where \(x\) is the # of people served single scoop and \(y\) the # of people served double scoop. Clearly insufficient to calculate single numerical value of \(y\). (2) A total of 120 scoops of icecream were served to all the guests at the picnic > \(1*x+2*y=120\). Again not sufficient. (1)+(2) \(x=\frac{2}{3}y\) and \(x+2y=120\): we have 2 distinct linear equations with 2 unknowns, hence we can solve for \(x\) and \(y\). Sufficient. (Just to illustrate: \(\frac{2}{3}y+2y=120\) > \(y=45\)) Answer: C.
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Re: At a certain picnic, each of the guests was served either a [#permalink]
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15 Oct 2012, 05:12
Let the total number of guests be 100x 1) 60x , where x can be anything >Insufficient 2) Clearly insufficient 1+2) No of guests who are served single scoop = 40x No of guests who are served double scoop = 60x Total no of scoops served  40x (1) + 60x(2) = 160x Total no of scoops served is 120 Thus 120 = 160x We can get Unique value of 60x which will 60x (120/160) = 45 >Sufficient Answer C
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Re: At a certain picnic, each of the guests was served either a [#permalink]
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15 Oct 2012, 08:57
1) Only a percentage is given. Nothing can be said from that. 60% of 10 is 6. 60% of 100 is 60 and so on. 2)Only total number of scoops served is given. It can be 50 ppl double scoop, 20 ppl single scoop or 40 ppl double scoop, 40 ppl single scoop and so on. 1 & 2 together 2*.6*x + 1*.4*x = 120 One equation, one unknown. Easily solvable. Hence answer is C 1.6*x = 120 x = 75 So. no. of ppl to whom double scoop was served = .6*75 = 45
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Re: At a certain picnic, each of the guests was served either a [#permalink]
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15 Oct 2012, 14:51
without any calculation we can solve DS (in this precise scenario) To have a solution we need total of the guests AND a % or a ratio or something to make the information manageable. otherwise we can't solve 1) we have a % but nothing else. insuff 2) we have the total but nothing else. insuff Together we have what we are looking for C \(must\) be the answerWe could save precious seconds for other questions, tougher.
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Re: At a certain picnic, each of the guests was served either a [#permalink]
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16 Oct 2012, 05:22
statement one we know the following double scoop = 0.60 X single scoop = 0.40 X no other information insufficient
statement 2 we are given the total and no other info again insufficient
combining 1 and 2
2*0.60X +0.40X = 120 1.20X +0.40X = 120 1.60X = 120 x=120/1.6 = 75
sufficient we didn't need to do the above steps we know there was 1 unknown and 1 equation
Answer is C



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Re: At a certain picnic, each of the guests was served either a [#permalink]
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16 Oct 2012, 06:19
Statement 1: Double scoop , D = 60% of Total, T => Single scoop, S= 40% of T => D/S=3/2 and D+S =T Not suff to find T. Statement 2: 2D +S =120 Not suff to find T. However combining two statements we have 2 equations to find S and D. And hence we can find T. Ans C. Bunuel wrote: The Official Guide for GMAT® Review, 13th Edition  Quantitative Questions ProjectAt a certain picnic, each of the guests was served either a single scoop or a double scoop of ice cream. How many of the guests were served a double scoop of ice cream? (1) At the picnic, 60 percent of the guests were served a double scoop of ice cream. (2) A total of 120 scoops of ice cream were served to all the guests at the picnic. Practice Questions Question: 61 Page: 280 Difficulty: 600 GMAT Club is introducing a new project: The Official Guide for GMAT® Review, 13th Edition  Quantitative Questions ProjectEach week we'll be posting several questions from The Official Guide for GMAT® Review, 13th Edition and then after couple of days we'll provide Official Answer (OA) to them along with a solution. We'll be glad if you participate in development of this project: 1. Please provide your solutions to the questions; 2. Please vote for the best solutions by pressing Kudos button; 3. Please vote for the questions themselves by pressing Kudos button; 4. Please share your views on difficulty level of the questions, so that we have most precise evaluation. Thank you!
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At a certain picnic, each of the guests was served either a [#permalink]
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23 Oct 2013, 05:25
Hello Bunuel,
Why can't we just assume that Y (double scope) = 2 X ?
So we will have X + 2 x = 120 hence B is enough.



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Re: At a certain picnic, each of the guests was served either a [#permalink]
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04 Feb 2014, 18:20
What if there was 100 people at the party, then 60 people get a double scoop (so 120 scoops are given out), and 0 people get single scoops? Based on this my answer was E since the problem states that people are served EITHER a single scoop OR double scoop. How can you answer this question without knowing how many people are at the party?



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At a certain picnic, each of the guests was served either a sing [#permalink]
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04 May 2014, 09:39
Bunuel wrote: Lstadt wrote: Hello Bunuel,
Why can't we just assume that Y (double scope) = 2 X ?
So we will have X + 2 x = 120 hence B is enough.
Because we don't know whether the # of guests who were served a single scoop of icecream (x) equals to the # of guests who were served a double scoop icecream (y). Hi Bunuel, I seemed to make the same mistake and still can't figure out why it's wrong. If we make equation B: S + 2S = 120, we get S = 40 and since 2S = D, the number of double scoops served to people were 80 scoops, therefore 40 double scoops therefore 40 people? This equation doesn't take into account the number of people at the picnic, so how are you assuming that the number of guests who indulged in the single scoop to be the same as the double scoop?



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Re: At a certain picnic, each of the guests was served either a [#permalink]
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04 May 2014, 10:57
russ9 wrote: Bunuel wrote: Lstadt wrote: Hello Bunuel,
Why can't we just assume that Y (double scope) = 2 X ?
So we will have X + 2 x = 120 hence B is enough.
Because we don't know whether the # of guests who were served a single scoop of icecream (x) equals to the # of guests who were served a double scoop icecream (y). Hi Bunuel, I seemed to make the same mistake and still can't figure out why it's wrong. If we make equation B: S + 2S = 120, we get S = 40 and since 2S = D, the number of double scoops served to people were 80 scoops, therefore 40 double scoops therefore 40 people? This equation doesn't take into account the number of people at the picnic, so how are you assuming that the number of guests who indulged in the single scoop to be the same as the double scoop? OK, maybe examples will help... (2) A total of 120 scoops of icecream were served to all the guests at the picnic. We can have the following cases: 0 single scoop icecream and 60 double scoop icecream were served. Number of people = 0 + 60 = 60. 2 single scoop icecream and 59 double scoop icecream were served. Number of people = 2 + 59 = 61. 4 single scoop icecream and 58 double scoop icecream were served. Number of people = 4 + 58 = 62. 6 single scoop icecream and 57 double scoop icecream were served. Number of people = 6 + 57 = 63. ... 118 single scoop icecream and 1 double scoop icecream were served. Number of people = 118 + 1 = 119. 120 single scoop icecream and 0 double scoop icecream were served. Number of people = 120 + 0 = 120. Please reread carefully solution here: atacertainpicniceachoftheguestswasservedeithera90254.html#p1041259
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At a certain picnic, each of the guests was served either a [#permalink]
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24 May 2015, 04:06
First theory (from MGMAT) Concrete valueIf a Data Sufficiency question asks for the concrete value of one element of a ratio, you will need BOTH the concrete value of another element of the ratio AND the relative value of two elements of the ratio. Relative valueIf a Data Sufficiency question asks for the relative value of two pieces of a ratio, ANY statement that gives the relative value of ANY two pieces of the ratio will be sufficient. We can solve this question using ratiosD= # of doubleScoop portions served T= # Total portions served (1) At the picnic, 60 percent of the guests were served a double scoop of ice cream. This statement tells us that the ratio of D/T = 3/5 Not Sufficient (See explanation above  we are asked to find the concrete Value) (2) A total of 120 scoops of ice cream were served to all the guests at the picnic. Not sufficient because we need add. a ratio od D/T to answer this question (1+2) D/S = 3/5 so we have 3x+5x = 120 X = 15 > D=3*15 =45 (C) Correct, can be calculated, BUT if you know the theory you don't need to calculate by DS Questions, it's enoough to know whether it can be calculated or not. Hope this helps
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Re: At a certain picnic, each of the guests was served either a [#permalink]
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13 Jan 2016, 22:40
Bunuel wrote: At a certain picnic, each of the guests was served either a single scoop or a double scoop icecream. How many of the guests were served a double scoop of icecream?
(1) At the picnic, 60 percent of the guests were served a double scoop of icecream > \(\frac{x}{y}=\frac{4}{6}=\frac{2}{3}\), where \(x\) is the # of people served single scoop and \(y\) the # of people served double scoop. Clearly insufficient to calculate single numerical value of \(y\).
(2) A total of 120 scoops of icecream were served to all the guests at the picnic > \(1*x+2*y=120\). Again not sufficient.
(1)+(2) \(x=\frac{2}{3}y\) and \(x+2y=120\): we have 2 distinct linear equations with 2 unknowns, hence we can solve for \(x\) and \(y\). Sufficient. (Just to illustrate: \(\frac{2}{3}y+2y=120\) > \(y=45\))
Answer: C. Hi Bunuel, probably a silly question but can you please tell me how you got the second equation? x is number of people served single scoop y is number of people served double scoop. So how can you assume that double the people had a double scoop??? x+2y=120



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Re: At a certain picnic, each of the guests was served either a [#permalink]
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14 Jan 2016, 00:22
sarathvr wrote: Bunuel wrote: At a certain picnic, each of the guests was served either a single scoop or a double scoop icecream. How many of the guests were served a double scoop of icecream?
(1) At the picnic, 60 percent of the guests were served a double scoop of icecream > \(\frac{x}{y}=\frac{4}{6}=\frac{2}{3}\), where \(x\) is the # of people served single scoop and \(y\) the # of people served double scoop. Clearly insufficient to calculate single numerical value of \(y\).
(2) A total of 120 scoops of icecream were served to all the guests at the picnic > \(1*x+2*y=120\). Again not sufficient.
(1)+(2) \(x=\frac{2}{3}y\) and \(x+2y=120\): we have 2 distinct linear equations with 2 unknowns, hence we can solve for \(x\) and \(y\). Sufficient. (Just to illustrate: \(\frac{2}{3}y+2y=120\) > \(y=45\))
Answer: C. Hi Bunuel, probably a silly question but can you please tell me how you got the second equation? x is number of people served single scoop y is number of people served double scoop. So how can you assume that double the people had a double scoop??? x+2y=120 If x the # of people served single scoop, then how many scoops of icecream those x people consume? 1*x. If y the # of people served double scoop, then how many scoops of icecream those y people consume? 2*y. So, if x+y people consumed 120 scoops, then 1*x + 2*y = 120.
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Re: At a certain picnic, each of the guests was served either a [#permalink]
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07 Jan 2017, 16:44
Why not do:
1)3/5(total)=double
2)total=120
1)+2) sufficient.
Am I oversimplifying this?



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Re: At a certain picnic, each of the guests was served either a [#permalink]
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17 Jan 2018, 06:49
I have a question here:
Why cant we do this? x being a single sccop of ice cream: x+ 2x= 120 , hence x =40 , 2x =80 => no of people = 40
and B sufficient.
+Bunuel



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Re: At a certain picnic, each of the guests was served either a [#permalink]
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17 Jan 2018, 07:30



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Re: At a certain picnic, each of the guests was served either a [#permalink]
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15 Jun 2018, 08:43
Bunuel wrote: SOLUTION
At a certain picnic, each of the guests was served either a single scoop or a double scoop icecream. How many of the guests were served a double scoop of icecream?
(1) At the picnic, 60 percent of the guests were served a double scoop of icecream > \(\frac{x}{y}=\frac{4}{6}=\frac{2}{3}\), where \(x\) is the # of people served single scoop and \(y\) the # of people served double scoop. Clearly insufficient to calculate single numerical value of \(y\).
(2) A total of 120 scoops of icecream were served to all the guests at the picnic > \(1*x+2*y=120\). Again not sufficient.
(1)+(2) \(x=\frac{2}{3}y\) and \(x+2y=120\): we have 2 distinct linear equations with 2 unknowns, hence we can solve for \(x\) and \(y\). Sufficient. (Just to illustrate: \(\frac{2}{3}y+2y=120\) > \(y=45\))
Answer: C. Hello, please how come its not alright to use a smart number for statement 1?




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