Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 44287

If Greg buys 3 shirts, 4 trousers and 2 ties, the total cost is $80. [#permalink]
Show Tags
19 Aug 2015, 01:32
1
This post received KUDOS
Expert's post
2
This post was BOOKMARKED
Question Stats:
44% (01:19) correct 56% (02:10) wrong based on 64 sessions
HideShow timer Statistics



Manager
Joined: 21 Jan 2015
Posts: 149
Location: India
Concentration: Strategy, Marketing
WE: Marketing (Consumer Products)

Re: If Greg buys 3 shirts, 4 trousers and 2 ties, the total cost is $80. [#permalink]
Show Tags
19 Aug 2015, 03:43
2
This post received KUDOS
Bunuel wrote: If Greg buys 3 shirts, 4 trousers and 2 ties, the total cost is $80. If Greg buys 7 shirts, 2 trousers and 2 ties, the total cost is $70. How much will it cost him to buy 3 trousers, 5 shirts and 2 ties?
A. $60 B. $64 C. $75 D. $96 E. Cannot be determined Ans: E Solution: 3x+4y+rz=80 & 7x+2y+2z=70 adding both the equations= 10x+6y+4z=150 5x+3y+2z=75 ans
_________________
 The Mind is Everything, What we Think we Become. Kudos will encourage many others, like me. Please Give Kudos !! Thanks



EMPOWERgmat Instructor
Status: GMAT Assassin/CoFounder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 11255
Location: United States (CA)
GRE 1: 340 Q170 V170

If Greg buys 3 shirts, 4 trousers and 2 ties, the total cost is $80. [#permalink]
Show Tags
04 Jan 2018, 16:05
Hi All, This prompt gives us 3 variables, but only 2 equations to work with. While a typical 'system' question will have the same number of variables (2 variables and 2 equations, for example), if a PS question provides you with an unequal number of variables and equations, there is ALWAYS a pattern (in terms of how the two equations 'interact' with one another) that you can use to answer the given question that is asked. To start, I'm going to call the variables: S = number of shirts T = number of trousers V = number of ties With the given information, we can create the following equations: 3S + 4T + 2V = 80 7S + 2T + 2V = 70 We're asked for the value of 5S + 3T + 2V.... Looking at the first variable in each equation, you should notice that 3S + 7S = 10S.... which is exactly DOUBLE the number of shirts we need. With the second variable, we have 4T+2T = 6T... which is exactly DOUBLE the number of shirts that we need. That is NOT a coincidence. If you add the two equations together, you get... 10S + 6T + 4V = 150 The question asks us for exactly HALF of that (5S + 3T + 2V), so we simply have to cut that equation 'in half': 5S + 3T + 2V = 75 Final Answer: GMAT assassins aren't born, they're made, Rich
_________________
760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com
Rich Cohen
CoFounder & GMAT Assassin
Special Offer: Save $75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee www.empowergmat.com/
***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************



Intern
Joined: 22 Aug 2017
Posts: 6

Re: If Greg buys 3 shirts, 4 trousers and 2 ties, the total cost is $80. [#permalink]
Show Tags
08 Jan 2018, 07:26
My first thought was to do ratios and find the unknown multiplier; however, that didn't work, but I am struggling to see why?
And I might have just answered my own question but I am not sure: Shirts, trousers, and ties are not worth the same so you have to solve for each variable?



Board of Directors
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 3349
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)

Re: If Greg buys 3 shirts, 4 trousers and 2 ties, the total cost is $80. [#permalink]
Show Tags
08 Jan 2018, 11:26
Bunuel wrote: If Greg buys 3 shirts, 4 trousers and 2 ties, the total cost is $80. If Greg buys 7 shirts, 2 trousers and 2 ties, the total cost is $70. How much will it cost him to buy 3 trousers, 5 shirts and 2 ties?
A. $60 B. $64 C. $75 D. $96 E. Cannot be determined
Kudos for a correct solution. 3s + 4t + 2e = 80> (I) 7s +2t + 2e = 70> (II) (I) + (II) = 10s + 6t + 4e = 150>(III) We are asked to find : Price of 3 trousers, 5 shirts and 2 ties So, the price of 3 trousers, 5 shirts and 2 ties will be (III)/2 = 75, answer will be (C)
_________________
Thanks and Regards
Abhishek....
PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS
How to use Search Function in GMAT Club  Rules for Posting in QA forum  Writing Mathematical Formulas Rules for Posting in VA forum  Request Expert's Reply ( VA Forum Only )



EMPOWERgmat Instructor
Status: GMAT Assassin/CoFounder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 11255
Location: United States (CA)
GRE 1: 340 Q170 V170

Re: If Greg buys 3 shirts, 4 trousers and 2 ties, the total cost is $80. [#permalink]
Show Tags
08 Jan 2018, 12:55
21savage21 wrote: My first thought was to do ratios and find the unknown multiplier; however, that didn't work, but I am struggling to see why?
And I might have just answered my own question but I am not sure: Shirts, trousers, and ties are not worth the same so you have to solve for each variable? Hi 21savage21, You're correct  we don't know what the individual clothing items cost (and there's no way to actually determine any of those prices)  so you can't answer the question in that way. Beyond that point though, neither of the two equations can be individually manipulated to answer the question that is asked, so you can't take that approach either. This question is a great example of how you should think critically about what you're specifically asked to solve for. If a question asks "what is the price of 1 shirt?", then the approach is likely fairly straightforward (and there will likely be more than one way to get to the solution). Here though, the question asks for the "total price of 3 trousers, 5 shirts and 2 ties"... and that is a WEIRD thing to ask for. This implies that the solution is likely "patternbased", so you really have to consider all of the information that you've been given (likely in ways that you wouldn't initially think of). GMAT assassins aren't born, they're made, Rich
_________________
760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com
Rich Cohen
CoFounder & GMAT Assassin
Special Offer: Save $75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee www.empowergmat.com/
***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************




Re: If Greg buys 3 shirts, 4 trousers and 2 ties, the total cost is $80.
[#permalink]
08 Jan 2018, 12:55






