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# M19-25

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Math Expert
Joined: 02 Sep 2009
Posts: 52390

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16 Sep 2014, 00:06
00:00

Difficulty:

25% (medium)

Question Stats:

72% (01:21) correct 28% (01:28) wrong based on 195 sessions

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A shop sells candy bars individually or in packs of 10. If the shop charges less for purchasing a pack of 10 candy bars than for purchasing 10 candy bars individually, then how much does the shop charge for purchasing a pack of 10 candy bars?

(1) The charge for purchasing a pack of 10 candy bars is $2 more than the charge for purchasing the 8 candy bars. (2) The charge for purchasing a pack of 10 candy bars is 10 percent less than the charge for purchasing the 10 candy bars individually. _________________ Math Expert Joined: 02 Sep 2009 Posts: 52390 Re M19-25 [#permalink] ### Show Tags 16 Sep 2014, 00:06 Official Solution: Say the price for purchasing a pack of 10 candy bars is $$x$$ and the price for purchasing the candy bar individually is $$y$$. (1) The charge for purchasing a pack of 10 candy bars is$2 more than the charge for purchasing the 8 candy bars. Given: $$x=8y+2$$. Two unknowns one equation. Not sufficient to calculate $$x$$.

(2) The charge for purchasing a pack of 10 candy bars is 10 percent less than the charge for purchasing the 10 candy bars individually. Given: $$x=0.9*10y$$. Two unknowns one equation. Not sufficient to calculate $$x$$.

(1)+(2) We have two distinct linear equations with two unknowns so we can solve for $$x$$ and $$y$$. Sufficient.

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Intern
Joined: 31 Mar 2016
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04 Sep 2017, 00:18
Hi there

Just wondering if the first stmt could be true by itself?

From the facts we understand that one pack of 10 is cheaper than 10 individual bars. I.e. X < 10Y

From first statement we have that X-8Y=2

If X is less than 10Y but must be greater than 8Y, could we say that it should be 9Y here. Or am I am I just assuming that it should be an integer..
Math Expert
Joined: 02 Sep 2009
Posts: 52390

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04 Sep 2017, 00:32
warmpied wrote:
Hi there

Just wondering if the first stmt could be true by itself?

From the facts we understand that one pack of 10 is cheaper than 10 individual bars. I.e. X < 10Y

From first statement we have that X-8Y=2

If X is less than 10Y but must be greater than 8Y, could we say that it should be 9Y here. Or am I am I just assuming that it should be an integer..

Yes, we are not told that x and y must be integers.
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Joined: 22 May 2017
Posts: 88
GMAT 1: 580 Q41 V29
GMAT 2: 580 Q43 V27

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20 Dec 2017, 19:07
Bunuel wrote:
warmpied wrote:
Hi there

Just wondering if the first stmt could be true by itself?

From the facts we understand that one pack of 10 is cheaper than 10 individual bars. I.e. X < 10Y

From first statement we have that X-8Y=2

If X is less than 10Y but must be greater than 8Y, could we say that it should be 9Y here. Or am I am I just assuming that it should be an integer..

Yes, we are not told that x and y must be integers.

Bunuel technically, how a candy bar can be integer.
I think answer should be A.
Math Expert
Joined: 02 Sep 2009
Posts: 52390

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20 Dec 2017, 19:25
Bunuel wrote:
warmpied wrote:
Hi there

Just wondering if the first stmt could be true by itself?

From the facts we understand that one pack of 10 is cheaper than 10 individual bars. I.e. X < 10Y

From first statement we have that X-8Y=2

If X is less than 10Y but must be greater than 8Y, could we say that it should be 9Y here. Or am I am I just assuming that it should be an integer..

Yes, we are not told that x and y must be integers.

Bunuel technically, how a candy bar can be integer.
I think answer should be A.

x = 8y + 2. Consider two cases:

x = 18 and y = 2 (notice x < 10y is satisfied);
x = 26 and y = 3 (notice x < 10y is satisfied).
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Intern
Joined: 11 Jan 2016
Posts: 11

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02 Aug 2018, 13:57
Bunuel Hi,

I statement -: If is 8 candy is X then 10Pack is X+2 .. Not suffi
II Statement -:if 10 candy individually X then 10 Pack would be 9/10X ... NO suffie

Combine -: 8/X* 10 *9/10 = X+2 ..Give X^2 +2x - 72 , so shouldn't the ans be E
Math Expert
Joined: 02 Sep 2009
Posts: 52390

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02 Aug 2018, 20:02
sunnyattri wrote:
Bunuel Hi,

I statement -: If is 8 candy is X then 10Pack is X+2 .. Not suffi
II Statement -:if 10 candy individually X then 10 Pack would be 9/10X ... NO suffie

Combine -: 8/X* 10 *9/10 = X+2 ..Give X^2 +2x - 72 , so shouldn't the ans be E

Let me ask you: what is the price for purchasing the candy bar individually in your equations? Is it x/8 or x/10? And could it be both? It's not clear what you've written there. It's better to denote by a variable the price for purchasing the candy bar individually.
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Joined: 11 Jan 2016
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02 Aug 2018, 22:14
@bunuel

let me ask you: what is the price for purchasing the candy bar individually in your equations? Is it x/8 or x/10? And could it be both? It's not clear what you've written there. It's better to denote by a variable the price for purchasing the candy bar individually.[/quote]

It's X/8 for one individual candy bar,so multiply by 10 to get the price for 10 Individual candy bar then i took 90% of that which in turn equal to X+2
Math Expert
Joined: 02 Sep 2009
Posts: 52390

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02 Aug 2018, 22:22
sunnyattri wrote:

It's X/8 for one individual candy bar,so multiply by 10 to get the price for 10 Individual candy bar then i took 90% of that which in turn equal to X+2

Then it should be x + 2 = (x/8*10)*0.9, which gives x = 16.
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Joined: 11 Jan 2016
Posts: 11

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02 Aug 2018, 22:28
sunnyattri wrote:

It's X/8 for one individual candy bar,so multiply by 10 to get the price for 10 Individual candy bar then i took 90% of that which in turn equal to X+2

Then it should be x + 2 = (x/8*10)*0.9, which gives x = 16.

Bunuel ya it should be! i don't know what calculation i did back there .. sorry for trouble and thanks.

But the approach is right?
Math Expert
Joined: 02 Sep 2009
Posts: 52390

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02 Aug 2018, 22:30
sunnyattri wrote:
sunnyattri wrote:

It's X/8 for one individual candy bar,so multiply by 10 to get the price for 10 Individual candy bar then i took 90% of that which in turn equal to X+2

Then it should be x + 2 = (x/8*10)*0.9, which gives x = 16.

Bunuel ya it should be! i don't know what calculation i did back there .. sorry for trouble and thanks.

But the approach is right?

Yes, x + 2 = (x/8*10)*0.9 is correct.
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Re: M19-25 &nbs [#permalink] 02 Aug 2018, 22:30
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# M19-25

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