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30 Dec 2009, 14:34
2
15
00:00

Difficulty:

95% (hard)

Question Stats:

58% (02:35) correct 42% (03:13) wrong based on 395 sessions

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Fox jeans regularly sell for $15 a pair and Pony jeans regularly sell for$18 a pair. During a sale these regular unit prices are discounted at different rates so that a total of $9 is saved by purchasing 5 pairs of jeans: 3 pairs of Fox jeans and 2 pairs of Pony jeans. If the sum of the two discounts rates is 22 percent, what is the discount rate on Pony jeans? A. 9% B. 10% C. 11% D. 12% E. 15% Math Expert Joined: 02 Sep 2009 Posts: 46297 Fox jeans regularly sell for$15 a pair and Pony jeans [#permalink]

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30 Dec 2009, 14:53
3
6
Fox jeans regularly sell for $15 a pair and Pony jeans regularly sell for$18 a pair. During a sale these regular unit prices are discounted at different rates so that a total of $9 is saved by purchasing 5 pairs of jeans: 3 pairs of Fox jeans and 2 pairs of Pony jeans. If the sum of the two discounts rates is 22 percent, what is the discount rate on Pony jeans? A. 9% B. 10% C. 11% D. 12% E. 15% x discount on Pony jeans, (0.22 - x) discount on Fox jeans. Set the equation: 3*15(0.22 - x) + 2*18x = 9 --> x = 0.1 = 10%. Answer: B. _________________ Senior Manager Joined: 22 Dec 2009 Posts: 324 Re: Disclosed GMAT Exam #42 Discounted Jeans [#permalink] ### Show Tags 01 Jan 2010, 10:42 Would go with B.... i.e. 10% Cheers! JT _________________ Cheers! JT........... If u like my post..... payback in Kudos!! |Do not post questions with OA|Please underline your SC questions while posting|Try posting the explanation along with your answer choice| |For CR refer Powerscore CR Bible|For SC refer Manhattan SC Guide| ~~Better Burn Out... Than Fade Away~~ Manager Joined: 27 Jul 2010 Posts: 172 Location: Prague Schools: University of Economics Prague Re: Disclosed GMAT Exam #42 Discounted Jeans [#permalink] ### Show Tags 02 Feb 2011, 11:09 Thanks bunuel, even faster solution than with 2 equasions. _________________ You want somethin', go get it. Period! Veritas Prep GMAT Instructor Joined: 16 Oct 2010 Posts: 8102 Location: Pune, India Re: Disclosed GMAT Exam #42 Discounted Jeans [#permalink] ### Show Tags 02 Feb 2011, 21:23 3 2 shanewyatt wrote: Can find total price without discount ($81) and price after discount ($72), but not sure where to go from there. Note: When I look at this question, my first instinct is to check if the split is 10% and 12%. The reason is that it is a lucky twin... i.e. when I split 22% to get one part as 10%, the other is 12%. When one part is 9%, the other is 13% (not there in options). When one part is 15%, the other is 7% (not there in options). 11% cannot be because the discount rates are different. I am not saying this strategy will always work, but this is what I will always start with because it has the maximum probability of being correct. Why? Because it is the tendency of the question setter to give one option as 12% too even if the correct answer is 10% because it is a pit for someone who is careless. Say, one found that the 22% is split into 10 and 12 but while answering the question, made a mistake of marking the discount on Fox jeans rather than Pony jeans... Bang! So watch out for lucky twins especially in probability questions! _________________ Karishma Veritas Prep | GMAT Instructor My Blog Get started with Veritas Prep GMAT On Demand for$199

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Re: Disclosed GMAT Exam #42 Discounted Jeans [#permalink]

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13 Mar 2011, 06:12
1
Let x be the discount on Fox Jeans
Let y be the discount on Pony Jeans

x + y = 22

x/100* 15 * 3 + y/100 * 18 * = 9

Solving these we get y = 10, so the answer is B.
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Re: Disclosed GMAT Exam #42 Discounted Jeans [#permalink]

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16 Apr 2011, 13:30
I follow the 10 / 12 split, but how would you end up choosing 10 over 12 using the lucky twin strategy for this question?

VeritasPrepKarishma wrote:
shanewyatt wrote:
Can find total price without discount ($81) and price after discount ($72), but not sure where to go from there.

Note: When I look at this question, my first instinct is to check if the split is 10% and 12%. The reason is that it is a lucky twin... i.e. when I split 22% to get one part as 10%, the other is 12%. When one part is 9%, the other is 13% (not there in options). When one part is 15%, the other is 7% (not there in options). 11% cannot be because the discount rates are different. I am not saying this strategy will always work, but this is what I will always start with because it has the maximum probability of being correct.

Why? Because it is the tendency of the question setter to give one option as 12% too even if the correct answer is 10% because it is a pit for someone who is careless. Say, one found that the 22% is split into 10 and 12 but while answering the question, made a mistake of marking the discount on Fox jeans rather than Pony jeans... Bang!

So watch out for lucky twins especially in probability questions!
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Posts: 1345
Re: Disclosed GMAT Exam #42 Discounted Jeans [#permalink]

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16 Apr 2011, 14:24
2
VeritasPrepKarishma wrote:
Note: When I look at this question, my first instinct is to check if the split is 10% and 12%. The reason is that it is a lucky twin... i.e. when I split 22% to get one part as 10%, the other is 12%. When one part is 9%, the other is 13% (not there in options). When one part is 15%, the other is 7% (not there in options). 11% cannot be because the discount rates are different. I am not saying this strategy will always work, but this is what I will always start with because it has the maximum probability of being correct.

Why? Because it is the tendency of the question setter to give one option as 12% too even if the correct answer is 10% because it is a pit for someone who is careless. Say, one found that the 22% is split into 10 and 12 but while answering the question, made a mistake of marking the discount on Fox jeans rather than Pony jeans... Bang!

So watch out for lucky twins especially in probability questions!

That might sound plausible, and I've certainly read about the 'trick' of identifying 'twin' answer choices many times, but in practice it is completely pointless to look for twinned answer choices. I looked at all the official questions in the OG and the Official Quant Review to see how often you'd answer correctly if you always guessed that a 'twin' answer was correct. It turns out you'd do (very slightly) worse by guessing a 'twin' than if you just guessed at random. I posted details here:

spaceland-prep-strategy-question-110923.html
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Re: Disclosed GMAT Exam #42 Discounted Jeans [#permalink]

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16 Apr 2011, 17:44
2
Let x and y are discount rates on Fox and Pony jeans respectively.

=> 3(15)(x) + 2*18(0.22-x) = 9

=> x = 12% and y =10%

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Re: Disclosed GMAT Exam #42 Discounted Jeans [#permalink]

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16 Apr 2011, 19:11
1
2
Yalephd wrote:
I follow the 10 / 12 split, but how would you end up choosing 10 over 12 using the lucky twin strategy for this question?

It is a guess. The way it helps me is that I will first check for the 10/12 split. If it doesn't work out, I will check the other options. You have to solve to get to the right answer.
Say if the % offered on Pony jeans ($18) is 10%, I am getting a discount of 1.8 on each pair of jeans. If I am getting 12% discount on Fox jeans($15), I am saving $1.8 on each pair of Fox jeans (you can calculate this orally and quickly - 10% of 15 is 1.5; 1% of 15 is 0.15 so 2% is 0.3, hence 12% of 15 is 1.5+0.3 =$1.8. If it seems too cumbersome, it is only because of lack of practice; it actually happens in a flash once you are used to it!)
On 3 pairs of Fox jeans and 2 pairs of Pony jeans, I will save 5*1.8 = $9 Since$9 is the given discount, our assumption is correct and the discount of Pony jeans must be 10%.
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Since $9 is the given discount, our assumption is correct and the discount of Pony jeans must be 10%. Veritas Prep GMAT Instructor Joined: 16 Oct 2010 Posts: 8102 Location: Pune, India Re: Disclosed GMAT Exam #42 Discounted Jeans [#permalink] ### Show Tags 17 Apr 2011, 17:58 1 gmat1220 wrote: Karishma Considering the weights - 3 and 2 (3 pairs of fox and 2 pairs of pony) - that he saved (12/10 discount) more by buying more of the fox jeans than pony jeans ? Is this thinking correct? i.e. more discount on the fox. Or the opposite He could have saved more by more discount on the pony - since the pony is priced for$3 more ($18 per pair) Hence we must rule out the option D before guessing option B. What do you think? I think the way you are thinking is pretty great but I did not understand what is 12/10 discount. If you want to consider weights, say, if you know that the answer is either 10-12 or 12-10, you can think this way: 3 Fox jeans price =$45
2 Pony jeans price = $36 So you got a discount of$9 on $81 which is 1/9 i.e. 11.11% discount. Since Fox jeans total cost price is higher than Pony jeans total cost price, the discount of Fox jeans must be 12% and that of Pony jeans must be 10% to give an average discount of 11.11% i.e. a value closer to 12% than to 10%. _________________ Karishma Veritas Prep | GMAT Instructor My Blog Get started with Veritas Prep GMAT On Demand for$199

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03 May 2014, 03:31
I prefer Bunel's equations, but here's another way:

We buy 3 Fox jeans : 3*15=45.
We buy 2 Pony jeans: 2*18=36.

45*discount fox + 36*discount pony = 9.

If the discount on the Pony jeans would be 9% ==> 36*0.09=3.24
Which means discount fox should be 13% ( To match the 22% in total)

12% of 45 = 5,85
And 5,85 + 3.24 = NOT 9 ( The total discount in $) Let's try answer B. ( I usually start with the most easy percentiles) 10% of 36 = 3,6 12% of 45 = 5,4 3,6+5,4=9 ==> We got a match! Answer B. _________________ Structural persistence is the key to succes . Party hard, study harder. Still bashing, will continue to do so , although it's important to chill aswell ; ) STUDY+CHILL=VICTORY SVP Status: The Best Or Nothing Joined: 27 Dec 2012 Posts: 1837 Location: India Concentration: General Management, Technology WE: Information Technology (Computer Software) Re: Fox jeans regularly sell for$15 a pair and Pony jeans [#permalink]

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01 Aug 2014, 02:35
Without discount, jeans selling price = 15 * 3 + 18 * 2 = 81

Discount = 9

With discount, selling price = 81-9 = 72

Say discount on Pony = x%; so discount on fox = (22-x)%

Setting up equation:

$$\frac{22-x}{100} * (15*3) + \frac{x}{100} * (18*2) = 9$$

x = 10

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26 Oct 2015, 01:17
Backsolve is good:

take C (11% each) means (11/100)*15*3+(11/100)*18*2 must be 9, but it is slightly less. So , it is B or D

take D (10% Pony and 12% Fox) means (10/100)*15*3+(12/100)*18*2 is more less than C

so B
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03 Sep 2017, 03:11
But what's wrong with the following logic?

"regular purchase cost - 9 saving =discounted purchase cost "

E.g. 3*15+2*18 - 9 = 3*15(1-x)+2*18(1-y)

45+36-9=45-45x+36-36y

Further we have a system of linear equations, from which we need to find out y

45x+36y=9
-
x+ y=22 /*45
------------------------
0+(-9y)=9-990

y=109