Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 50010

Question Stats:
57% (04:41) correct 43% (01:54) wrong based on 235 sessions
HideShow timer Statistics



Math Expert
Joined: 02 Sep 2009
Posts: 50010

Official Solution: Bonnie and Clyde, when working together, complete the painting of the car in \(\frac{xy}{x+y}\) hours (sum of the rates equal to the combined rate or reciprocal of total time: \(\frac{1}{x}+\frac{1}{y}=\frac{1}{T}\). From that we can get that \(T=\frac{xy}{x+y}\)). Now, if \(x=y\), then the total time would be: \(\frac{x^2}{2x}=\frac{x}{2}\), since \(x\) is odd, then this time would be \(\frac{odd}{2}\): 0.5 hours, 1.5 hours, 2.5 hours, ... (1) \(x^2+y^2 \lt 12\). It's possible that \(x\) and \(y\) are odd and equal each other if \(x=y=1\), but it's also possible that \(x=1\) and \(y=3\) (or viseversa). Not sufficient. (2) Bonnie and Clyde complete the painting of the car at 10:30am. They complete the job in \(\frac{3}{4}\) of an hour (45 minutes), since it's not \(\frac{odd}{2}\) then \(x\) and \(y\) are not equal. Sufficient. Answer: B
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Intern
Joined: 14 Jan 2012
Posts: 9

Re: M2711
[#permalink]
Show Tags
24 Sep 2014, 12:30
Quote: Now, if x=y, then the total time would be: \frac{x^2}{2x}=\frac{x}{2}, since x is odd, then this time would be either an integer or \frac{integer}{2}: 0.5 hours, 1 hour, 1.5 hours, .... I don't get it: odd/2 can not be integer, so how did we get 1 hour?



Math Expert
Joined: 02 Sep 2009
Posts: 50010

Re: M2711
[#permalink]
Show Tags
25 Sep 2014, 02:00
Boycot wrote: Quote: Now, if x=y, then the total time would be: \frac{x^2}{2x}=\frac{x}{2}, since x is odd, then this time would be either an integer or \frac{integer}{2}: 0.5 hours, 1 hour, 1.5 hours, .... I don't get it: odd/2 can not be integer, so how did we get 1 hour? You are right. Edited. Thank you.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Current Student
Joined: 02 May 2015
Posts: 29
Location: India
Concentration: Operations, Economics
GPA: 3.76
WE: Operations (Energy and Utilities)

(1) x2+y2<12. It's possible that x and y are odd and equal each other if x=y=1, but it's also possible that x=1 and y=3 (or viseversa). Not sufficient. I don't get this....clearly x=y=1 is not possible since we are given that both of them took 45 minutes and if x=y=1 then, they shud have taken 30 minutes...so the only option is x=1 & y=3 (vice versa) hence, sufficient. Bunuel ..please correct me .



Math Expert
Joined: 02 Sep 2009
Posts: 50010

Re: M2711
[#permalink]
Show Tags
09 Nov 2015, 04:26



Current Student
Joined: 02 May 2015
Posts: 29
Location: India
Concentration: Operations, Economics
GPA: 3.76
WE: Operations (Energy and Utilities)

Re: M2711
[#permalink]
Show Tags
09 Nov 2015, 04:33
Hmm....Thanks...I mixed statement two with the question stem... ...sorry



Current Student
Joined: 12 Aug 2015
Posts: 287
Concentration: General Management, Operations
GMAT 1: 640 Q40 V37 GMAT 2: 650 Q43 V36 GMAT 3: 600 Q47 V27
GPA: 3.3
WE: Management Consulting (Consulting)

Re: M2711
[#permalink]
Show Tags
12 Nov 2015, 22:50
"simultaneously" is fine but "independently" has confused me  why should we imply that they work on one and the same car but not on 2 identical cars simultaneously and independently? the 1st para only sets the individual rates.
_________________
KUDO me plenty



Math Expert
Joined: 02 Sep 2009
Posts: 50010

Re: M2711
[#permalink]
Show Tags
13 Nov 2015, 00:41
shasadou wrote: "simultaneously" is fine but "independently" has confused me  why should we imply that they work on one and the same car but not on 2 identical cars simultaneously and independently?
the 1st para only sets the individual rates. "Work simultaneously and independently" means that the they work on unique parts of the job (in this case, if one person paints the left side of the car, the other person WON'T ALSO paint the left side of the car). This is important to the math because the idea is that the entire car will be painted, but it will be done in the fastest way possible (with no duplicated work). It's the type of "legalese" that has to be included in the question, otherwise the correct answer could be debated.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Manager
Status: One Last Shot !!!
Joined: 04 May 2014
Posts: 239
Location: India
Concentration: Marketing, Social Entrepreneurship
GMAT 1: 630 Q44 V32 GMAT 2: 680 Q47 V35

Given: 1. Bonnie takes x hrs to do a job 2. Clyde takes y hrs to do the same job 3. Both start independently at the same time 9:45am 4. x and y are odd integers to find: x=y ? S1: \(x^2+y^2 \lt 12\) Since we already know that x and y are Odd integers, there's not much left to check for in the above condition and since adding two squares will very soon pass such a small number as 12, we can do the manual work here x=1; y=1 => Yes (both equal and sum of squares less than 12) x=1; y=3 => No (both unequal and still the sum of squares less than 12) Hence NS S2: Bonnie and Clyde complete the painting of the car at 10:30amQuite straightforward. Basically, they started at the same time and ended at the same time. Therefore, we can certainly infer that the time they took was same \(x=y\) Hence S B
_________________
One Kudos for an everlasting piece of knowledge is not a bad deal at all...
 Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover. Mark Twain



Manager
Joined: 11 Feb 2015
Posts: 78
Location: United States
Concentration: Strategy, General Management
GPA: 3.7
WE: Engineering (Energy and Utilities)

Re: M2711
[#permalink]
Show Tags
08 Nov 2016, 19:31
BunuelIt is a very good question. But, don't you think it is necessary to mention that they worked simultaneously and independently on the same car? I understand it is important to mention that they worked independently, but it is worded in such a way that reader can interpret that they are working on two different cars which are same/identical.



Manager
Status: One Last Shot !!!
Joined: 04 May 2014
Posts: 239
Location: India
Concentration: Marketing, Social Entrepreneurship
GMAT 1: 630 Q44 V32 GMAT 2: 680 Q47 V35

Re: M2711
[#permalink]
Show Tags
08 Nov 2016, 21:21
sveniga4 wrote: BunuelIt is a very good question. But, don't you think it is necessary to mention that they worked simultaneously and independently on the same car? I understand it is important to mention that they worked independently, but it is worded in such a way that reader can interpret that they are working on two different cars which are same/identical. Here's my take Even if you infer that ' ...they are working on two different cars which are same/identical', it is Okay! Because the main thing that needs to be understood is that both do the same amount of work, and that they started at the same timeAt least, this is what i understood from the prompt after the first read, please correct me if im wrong.
_________________
One Kudos for an everlasting piece of knowledge is not a bad deal at all...
 Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover. Mark Twain



Manager
Joined: 11 Feb 2015
Posts: 78
Location: United States
Concentration: Strategy, General Management
GPA: 3.7
WE: Engineering (Energy and Utilities)

Re: M2711
[#permalink]
Show Tags
08 Nov 2016, 21:41
arhumsid wrote: sveniga4 wrote: BunuelIt is a very good question. But, don't you think it is necessary to mention that they worked simultaneously and independently on the same car? I understand it is important to mention that they worked independently, but it is worded in such a way that reader can interpret that they are working on two different cars which are same/identical. Here's my take Even if you infer that ' ...they are working on two different cars which are same/identical', it is Okay! Because the main thing that needs to be understood is that both do the same amount of work, and that they started at the same timeAt least, this is what i understood from the prompt after the first read, please correct me if im wrong. We can not conclude that they both did the same amount of work or their rate of work is equal. For example, A can paint 3/4th of the car whereas B can pain 1/4th of the car.



Manager
Status: One Last Shot !!!
Joined: 04 May 2014
Posts: 239
Location: India
Concentration: Marketing, Social Entrepreneurship
GMAT 1: 630 Q44 V32 GMAT 2: 680 Q47 V35

Re: M2711
[#permalink]
Show Tags
08 Nov 2016, 21:51
sveniga4 wrote: arhumsid wrote: sveniga4 wrote: BunuelIt is a very good question. But, don't you think it is necessary to mention that they worked simultaneously and independently on the same car? I understand it is important to mention that they worked independently, but it is worded in such a way that reader can interpret that they are working on two different cars which are same/identical. Here's my take Even if you infer that ' ...they are working on two different cars which are same/identical', it is Okay! Because the main thing that needs to be understood is that both do the same amount of work, and that they started at the same timeAt least, this is what i understood from the prompt after the first read, please correct me if im wrong. We can not conclude that they both did the same amount of work or their rate of work is equal. For example, A can paint 3/4th of the car whereas B can pain 1/4th of the car. Yes indeed, i was wrong. We cannot say that both did the same amount of work. That was a really bad choice of words at my end Thanks for correcting me. But, can we not assume that both worked on the same/identical cars?
_________________
One Kudos for an everlasting piece of knowledge is not a bad deal at all...
 Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover. Mark Twain



Senior Manager
Status: You have to have the darkness for the dawn to come
Joined: 09 Nov 2012
Posts: 299
Daboo: Sonu
GMAT 1: 590 Q49 V20 GMAT 2: 730 Q50 V38

Re: M2711
[#permalink]
Show Tags
03 Mar 2017, 03:23
Please explain in detail how b is correct
_________________
You have to have the darkness for the dawn to come.
Give Kudos if you like my post



Math Expert
Joined: 02 Sep 2009
Posts: 50010

Re: M2711
[#permalink]
Show Tags
03 Mar 2017, 03:27



Manager
Joined: 03 Jan 2017
Posts: 157

Re: M2711
[#permalink]
Show Tags
06 May 2017, 02:42
I approached the question this way: 1) clear
2) Rate of Bonnie is 1/b, rate of Clyde 1/c. They work together at rate (b+c)/bc. And to paint a car it will take bc/(b+c) hours as we know that they work for 3/4 hours, we can say bc/(b+c)=3/4. As we know b,c are odd integers, we can infer that b and c are 3 and 1, hence not the same



Intern
Joined: 19 Jun 2017
Posts: 11

Re: M2711
[#permalink]
Show Tags
15 Aug 2017, 18:53
Perhaps another approach is via inversion: set x=y and check if question stem constraint that x and y are ODD integers holds.
(1) Insufficient since x and y could be either same or different odd integers
(2) T = xy/(y+x) = 3/4 hour
Let x=y=2n+1, i.e. representing an odd integer Thus we have: (2n+1)^2 / [2(2n+1)] = 3/4  cross multiply, reduce...  16n^2 + 16n + 4 = 12n + 6 8n^2 + 2n  1 = 0 (8n + 4)(n  1/4) = 0 n1 = 1/2 n2 = 1/4
Plugging n1 & n2 back into x=y=2n+1 gives us x = 0 hours (invalid) or x = 1.5 hours (valid) Therefore, if x=y, then x and y cannot both be odd integers according statement 2's parameters (said another way, if x and y are both odd integers, then x cannot = y) => Sufficient



Intern
Joined: 24 Oct 2016
Posts: 29

Re: M2711
[#permalink]
Show Tags
16 Sep 2017, 04:25
Explanation of part B:
Given that both completed the work in 3/4 hours, we can write it as 1/x+1/y=1/(3/4)............(A)
Lets assume x=y ...........(B)
Using (A) and (B) we get x=3/2
However, from the question stem, x is an odd integer.
Therefore, our assumtion x=y is incorrect.
Correct answer B.



Intern
Joined: 31 Aug 2017
Posts: 1

Re: M2711
[#permalink]
Show Tags
16 Sep 2017, 04:33
Thanks kishor! That was helpful







Go to page
1 2
Next
[ 28 posts ]



