December 11, 2018 December 11, 2018 09:00 PM EST 10:00 PM EST Strategies and techniques for approaching featured GMAT topics. December 11 at 9 PM EST. December 13, 2018 December 13, 2018 08:00 AM PST 09:00 AM PST What people who reach the high 700's do differently? We're going to share insights, tips and strategies from data we collected on over 50,000 students who used examPAL.
Author 
Message 
TAGS:

Hide Tags

Manager
Joined: 13 Oct 2013
Posts: 136
Concentration: Strategy, Entrepreneurship

If a certain company purchased computers at $2000 each and printers $
[#permalink]
Show Tags
Updated on: 06 Sep 2015, 03:28
Question Stats:
69% (01:19) correct 31% (01:22) wrong based on 160 sessions
HideShow timer Statistics
If a certain company purchased computers at $2000 each and printers $300 each , how many computers did it purchase? (1) More than three printers were purchased (2) The total amount for the purchase of the computers and printers was $15,000
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
 Kindly press +1 Kudos if my post helped you in any way
Originally posted by sunita123 on 05 Sep 2015, 22:08.
Last edited by Bunuel on 06 Sep 2015, 03:28, edited 1 time in total.
Renamed the topic and edited the question.



Intern
Joined: 21 Oct 2014
Posts: 6

Re: If a certain company purchased computers at $2000 each and printers $
[#permalink]
Show Tags
05 Sep 2015, 23:45
Yes E is correct. I will explain how.
Statement 1 is clearly not sufficient.
Statement 2 says That the total was 15,000.
So (c)2000 + (p)300 = 15,000 where p is for printers and c is for computers.
when p=10 then the remaining amount left for computers is 12000 which means 6 computers.
but when p=30 the then the remaining amount left is 15,000  30(300) = 6000 which means 3 computers. Different values means the statement is insufficient
Combining:
St. 1 says p>3 St. 2 says (c)2000 + (p)300 = 15,000.
But we know that the number of printers has to be a minimum of 10 for the remaining amount to be a multiple of 2000. ( from ST. 2) Combining does not help because p>10 from statement 2. and statement 1 says p>3. p>10 is the more limiting inequality so we use that but it will not get us the answer.
So the answer is E.
The easiest approach according to me: Start subtracting multiples of 300 from 15000 till you get a multiple of 2000.
15,000300 = 14,700( not a multiple of 2000) 15,000 600 = 14,400(not a multiple of 2000) till you get to 15,000  3000 = 12,000 (Bingo you found the multiple)
Now you have to check if any other value of p satisfies the equation. 15,000 9,000 = 6000( multiple of 2000)
So answer is E.
Hope this helps!



Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 6619
GPA: 3.82

If a certain company purchased computers at $2000 each and printers $
[#permalink]
Show Tags
06 Sep 2015, 19:42
Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and equations ensures a solution. If a certain company purchased computers at $2000 each and printers $300 each , how many computers did it purchase? 1) more than three printers were purchased 2) The total amount for the purchase of the computers and printers was $15,000 Transforming the original condition by variable approach method, we have 2 variables (number of computers;x, number of printers:y) and since we need to match the number of variables and equations, we need 2 equations. Since there is 1 each in 1) and 2), C is likely the answer. Using both 1) & 2) together, 2000x+300y=15000 ==> 20x+3y=150. then we have pair (x,y)=(3,30), (6,10), and since the answer is Not unique the conditions are not sufficient. Therefore the answer is E.
_________________
MathRevolution: Finish GMAT Quant Section with 10 minutes to spare The oneandonly World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. "Only $99 for 3 month Online Course" "Free Resources30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons  try it yourself"



Retired Moderator
Joined: 29 Oct 2013
Posts: 260
Concentration: Finance
GPA: 3.7
WE: Corporate Finance (Retail Banking)

If a certain company purchased computers at $2000 each and printers $
[#permalink]
Show Tags
18 Jan 2016, 09:19
VeritasPrepKarishma and other experts: The answer is not B as the LCM of 2000 and 300 is less than 15,000. This is the reason the equation will not form a Diophantine equation and will not result in a unique solution. I think my logic is sound. But can you pls comment on my logic and if I can use it reliably on similar questions, in which, it ultimately comes down to unicity or plurality of solution to an equation, without testing numbers? thanks
_________________
Please contact me for super inexpensive quality private tutoring
My journey V46 and 750 > http://gmatclub.com/forum/myjourneyto46onverbal750overall171722.html#p1367876



CEO
Joined: 20 Mar 2014
Posts: 2633
Concentration: Finance, Strategy
GPA: 3.7
WE: Engineering (Aerospace and Defense)

Re: If a certain company purchased computers at $2000 each and printers $
[#permalink]
Show Tags
18 Jan 2016, 09:47
NoHalfMeasures wrote: VeritasPrepKarishma and other experts: The answer is not B as the LCM of 2000 and 300 is less than 15,000. This is the reason the equation will not form a Diophantine equation and will not result in a unique solution. I think my logic is sound. But can you pls comment on my logic and if I can use it reliably on similar questions, in which, it ultimately comes down to unicity or plurality of solution to an equation, without testing numbers? thanks Dont know about the application of diophantine equation to other similar questions but this is how I would solve this question. You are given that each computer costs 2000 while each printer costs 300. You need to find the # of computers = c. Per statement 1, p>3. Clearly not sufficient. Per statement 2, 2000c+300p=15000 > 20c+3p=150. Solution sets for (c,p) can be (6,10) or (3,30). Thus no unique solution. Not sufficient. Combining the 2 statements, still the 2 solution sets above (6,10) or (3,30) are applicable and hence E is the correct answer as you do not get a unique solution for the number of computers. Hope this helps.



Retired Moderator
Joined: 29 Oct 2013
Posts: 260
Concentration: Finance
GPA: 3.7
WE: Corporate Finance (Retail Banking)

Re: If a certain company purchased computers at $2000 each and printers $
[#permalink]
Show Tags
18 Jan 2016, 10:09
Thanks for your reply Engr2012. However, I know how to solve it using conventional methods. Im more interested in conceptual understanding of my logic and its applicability to similar questions. thanks again
_________________
Please contact me for super inexpensive quality private tutoring
My journey V46 and 750 > http://gmatclub.com/forum/myjourneyto46onverbal750overall171722.html#p1367876



Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 6619
GPA: 3.82

Re: If a certain company purchased computers at $2000 each and printers $
[#permalink]
Show Tags
18 Jan 2016, 21:10
Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution. If a certain company purchased computers at $2000 each and printers $300 each , how many computers did it purchase? (1) More than three printers were purchased (2) The total amount for the purchase of the computers and printers was $15,000 When you modify the original condition and the question, it is frequently given on GMAT Math test which is "2 by 2" que. Attachment:
GCDS sunita123 If a certain company purchased (20160119).jpg [ 25.83 KiB  Viewed 2233 times ]
On the table, there are 2 variables(a,b), which should match with the number of equations. So you need 2 equations. For 1) 1 equation, for 2) 1 equation, which is likely to make C the answer. When 1) & 2), 2000a+200b=15000 > 20a+3b=150 > (a,b)=(3,30),(6,10), which is not unique and not sufficient. Therefore, the answer is E. For cases where we need 2 more equations, such as original conditions with “2 variables”, or “3 variables and 1 equation”, or “4 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 70% chance that C is the answer, while E has 25% chance. These two are the majority. In case of common mistake type 3,4, the answer may be from A, B or D but there is only 5% chance. Since C is most likely to be the answer using 1) and 2) separately according to DS definition (It saves us time). Obviously there may be cases where the answer is A, B, D or E.
_________________
MathRevolution: Finish GMAT Quant Section with 10 minutes to spare The oneandonly World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. "Only $99 for 3 month Online Course" "Free Resources30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons  try it yourself"



Director
Joined: 26 Oct 2016
Posts: 641
Location: United States
Concentration: Marketing, International Business
GPA: 4
WE: Education (Education)

Re: If a certain company purchased computers at $2000 each and printers $
[#permalink]
Show Tags
12 Feb 2017, 21:15
Statement (1); Says nothing about computers Statement (2): From the stem we know that the total purchase of computers and printers can be expressed as: 2000c + 300p From this statement, we know that sum will be $15,000, so: 15000 = 2000c + 300p This is a single expression with TWO variables so it is unlikely to give us a unique (integer) value for both of our variables, but we can see what pairs would work: First we check the high priced item, Computers. 0 comp = 0 (15,000 left for printers = 50 printers) 1 comp = 2,000 (13,000 left for printers = NOT WHOLE # of printers) 2 comps = 4,000 (11,000 left for printers = NOT WHOLE # of printers) 3 comps = 6,000 (9,000 left for printers = 30 printers) 4 comps = 8,000 (7,000 left for printers = NOT WHOLE # of printers) 5 comps = 10,000 (5,000 left for printers = NOT WHOLE # of printers) 6 comps = 12,000 (3,000 left for printers = 10 printers) 7 comps = 14,000 (1,000 left for printers = NOT WHOLE # of printers) 8 comps = TOO MUCH So statement (2) gives 3 possible outcomes:  0 computers and 50 printers  3 computers and 30 printers  6 computers and 10 printers Statement (1+2) We have not eliminated any of the possible scenarios from statement (1) because in ALL cases more than 3 printers were purchased. The correct answer is E
_________________
Thanks & Regards, Anaira Mitch



Intern
Joined: 16 Aug 2015
Posts: 9

Re: If a certain company purchased computers at $2000 each and printers $
[#permalink]
Show Tags
17 Jul 2017, 17:17
Engr2012 wrote: NoHalfMeasures wrote: VeritasPrepKarishma and other experts: The answer is not B as the LCM of 2000 and 300 is less than 15,000. This is the reason the equation will not form a Diophantine equation and will not result in a unique solution. I think my logic is sound. But can you pls comment on my logic and if I can use it reliably on similar questions, in which, it ultimately comes down to unicity or plurality of solution to an equation, without testing numbers? thanks Dont know about the application of diophantine equation to other similar questions but this is how I would solve this question. You are given that each computer costs 2000 while each printer costs 300. You need to find the # of computers = c. Per statement 1, p>3. Clearly not sufficient. Per statement 2, 2000c+300p=15000 > 20c+3p=150. Solution sets for (c,p) can be (6,10) or (3,30). Thus no unique solution. Not sufficient. Combining the 2 statements, still the 2 solution sets above (6,10) or (3,30) are applicable and hence E is the correct answer as you do not get a unique solution for the number of computers. Hope this helps. Hello Engr2012, Bunuel, What is a good way to reach the two solutions (6,10) or (3,30), from the equation 20c + 3p = 150? looks like a lot of these DS word problems hinge on determining whether there are 1 or 1+ solutions to these equations.



NonHuman User
Joined: 09 Sep 2013
Posts: 9103

Re: If a certain company purchased computers at $2000 each and printers $
[#permalink]
Show Tags
24 Nov 2018, 12:38
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.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources




Re: If a certain company purchased computers at $2000 each and printers $ &nbs
[#permalink]
24 Nov 2018, 12:38






