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

Math Expert
Joined: 02 Sep 2009
Posts: 51099

Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
18 Mar 2014, 00:39
Question Stats:
56% (03:10) correct 44% (03:13) wrong based on 1148 sessions
HideShow timer Statistics
The Official Guide For GMAT® Quantitative Review, 2ND EditionRunning at their respective constant rates, Machine X takes 2 days longer to produce w widgets than Machine Y. At these rates, if the two machines together produce (5/4)w widgets in 3 days, how many days would it take Machine X alone to produce 2w widgets? (A) 4 (B) 6 (C) 8 (D) 10 (E) 12 Problem Solving Question: 173 Category: Algebra; Applied problems Page: 85 Difficulty: 600 GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition  Quantitative Questions ProjectEach week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution. We'll be glad if you participate in development of this project: 1. Please provide your solutions to the questions; 2. Please vote for the best solutions by pressing Kudos button; 3. Please vote for the questions themselves by pressing Kudos button; 4. Please share your views on difficulty level of the questions, so that we have most precise evaluation. Thank you!
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
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




Math Expert
Joined: 02 Sep 2009
Posts: 51099

Re: Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
18 Mar 2014, 00:39
SOLUTIONRunning at their respective constant rates, Machine X takes 2 days longer to produce w widgets than Machine Y. At these rates, if the two machines together produce (5/4)w widgets in 3 days, how many days would it take Machine X alone to produce 2w widgets?(A) 4 (B) 6 (C) 8 (D) 10 (E) 12 For work problems one of the most important thin to know is \(rate*time=job \ done\). Let the time needed for machine X to produce \(w\) widgets be \(t\) days, so the rate of X would be \(rate=\frac{job \ done}{time}=\frac{w}{t}\); As "machine X takes 2 days longer to produce \(w\) widgets than machines Y" then time needed for machine Y to produce \(w\) widgets would be \(t2\) days, so the rate of Y would be \(rate=\frac{job \ done}{time}=\frac{w}{t2}\); Combined rate of machines X and Y in 1 day would be \(\frac{w}{t}+\frac{w}{t2}\) (remember we can sum the rates). In 3 days two machines together produce 5w/4 widgets so: \(3(\frac{w}{t}+\frac{w}{t2})=\frac{5w}{4}\) > \(\frac{w}{t}+\frac{w}{t2}=\frac{5w}{12}\). \(\frac{w}{t}+\frac{w}{t2}=\frac{5w}{12}\) > reduce by \(w\) > \(\frac{1}{t}+\frac{1}{t2}=\frac{5}{12}\). At this point we can either solve quadratic equation: \(5t^234t+24=0\) > \((t6)(5t4)=0\) > \(t=6\) or \(t=\frac{4}{5}\) (which is not a valid solution as in this case \(t2=\frac{6}{5}\), the time needed for machine Y to ptoduce \(w\) widgets will be negatrive value and it's not possible). So \(t=6\) days is needed for machine X to produce \(w\) widgets, hence time needed for machine X to produce \(2w\) widgets will be \(2t=12\) days. OR try to substitute the values from the answer choices. Remember as we are asked to find the time needed for machine X alone to produce \(2w\) widgets then the answer should be \(2t\) among answer choices: E work  \(2t=12\) > \(t=6\) > \(\frac{1}{6}+\frac{1}{62}=\frac{5}{12}\). Answer: E.
_________________
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




SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1825
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)

Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
Updated on: 14 Aug 2014, 02:01
Time taken by Machine Y = t days Time taken by Machine X = (t+2) days Rate of Machine \(X = \frac{w}{t+2}\) Rate of Machine \(Y = \frac{w}{t}\) \(\frac{5w}{4}\) widgets produced in 3 days; so \(\frac{5w}{12}\) produced in 1 day Equation setup will be \(\frac{w}{t+2} + \frac{w}{t} = \frac{5w}{12}\) Solving, \(5t^2  14t  24 = 0\) t = 4 Time taken by Machine X = t+2 = 6 for w So for 2w; it will be 12
Answer = E
_________________
Kindly press "+1 Kudos" to appreciate
Originally posted by PareshGmat on 20 Mar 2014, 00:52.
Last edited by PareshGmat on 14 Aug 2014, 02:01, edited 1 time in total.




Math Expert
Joined: 02 Sep 2009
Posts: 51099

Re: Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
23 Mar 2014, 07:13
SOLUTIONRunning at their respective constant rates, Machine X takes 2 days longer to produce w widgets than Machine Y. At these rates, if the two machines together produce (5/4)w widgets in 3 days, how many days would it take Machine X alone to produce 2w widgets?(A) 4 (B) 6 (C) 8 (D) 10 (E) 12 For work problems one of the most important thin to know is \(rate*time=job \ done\). Let the time needed for machine X to produce \(w\) widgets be \(t\) days, so the rate of X would be \(rate=\frac{job \ done}{time}=\frac{w}{t}\); As "machine X takes 2 days longer to produce \(w\) widgets than machines Y" then time needed for machine Y to produce \(w\) widgets would be \(t2\) days, so the rate of Y would be \(rate=\frac{job \ done}{time}=\frac{w}{t2}\); Combined rate of machines X and Y in 1 day would be \(\frac{w}{t}+\frac{w}{t2}\) (remember we can sum the rates). In 3 days two machines together produce 5w/4 widgets so: \(3(\frac{w}{t}+\frac{w}{t2})=\frac{5w}{4}\) > \(\frac{w}{t}+\frac{w}{t2}=\frac{5w}{12}\). \(\frac{w}{t}+\frac{w}{t2}=\frac{5w}{12}\) > reduce by \(w\) > \(\frac{1}{t}+\frac{1}{t2}=\frac{5}{12}\). At this point we can either solve quadratic equation: \(5t^234t+24=0\) > \((t6)(5t4)=0\) > \(t=6\) or \(t=\frac{4}{5}\) (which is not a valid solution as in this case \(t2=\frac{6}{5}\), the time needed for machine Y to ptoduce \(w\) widgets will be negatrive value and it's not possible). So \(t=6\) days is needed for machine X to produce \(w\) widgets, hence time needed for machine X to produce \(2w\) widgets will be \(2t=12\) days. OR try to substitute the values from the answer choices. Remember as we are asked to find the time needed for machine X alone to produce \(2w\) widgets then the answer should be \(2t\) among answer choices: E work  \(2t=12\) > \(t=6\) > \(\frac{1}{6}+\frac{1}{62}=\frac{5}{12}\). Answer: E.
_________________
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: 13 Feb 2014
Posts: 6

Re: Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
16 May 2014, 06:22
QE: 5t^2  14t  24 = 0, How do we get solution = 4?



Math Expert
Joined: 02 Sep 2009
Posts: 51099

Re: Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
16 May 2014, 08:32



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

Re: Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
27 May 2014, 14:16
Alternate Solution without algebra using POE. If it takes 3 days to produce 5/4 widgets, it will take 3*(4/5) = 12/5 days to produce 1 widget. If two machines were working at the same rate it would take, 2*12/5 i.e. approx 5 days days for x to produce 1 widget. Since machine X is slower it will take more than 5 days to produce 1 widget and subsequently more than 10 days to produce 2 widgets. The only answer more than 10 is 12 days. Answer E
_________________
Please contact me for super inexpensive quality private tutoring
My journey V46 and 750 > http://gmatclub.com/forum/myjourneyto46onverbal750overall171722.html#p1367876



Manager
Joined: 17 Oct 2012
Posts: 65
Location: India
Concentration: Strategy, Finance
WE: Information Technology (Computer Software)

Re: Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
10 Aug 2014, 01:25
Back tracking method: We have to find the number of days it takes Machine X alone to produce 2w widgets. Answer options are as below:
(A) 4 (B) 6 (C) 8 (D) 10 (E) 12
We are given that X and Y produce (5/4)w in 3 days and also given that X take 2 days more than Y. So to find corresponding value of X and Y use the answer options. First half the value of X to find number of days it takes Machine X to complete *W* widgets and find the value of Y by reducing 2 from all answer options.
> X to complete W widgets (A) X=2 and Y= 22 =0 (B) X=3 and Y= 32 =1 (C) X=4 and Y= 42 =2 (D) X=5 and Y= 52 =3 (E) X=6 and Y= 62 =4
Now we have all the values of X and Y. Find out the combination X and Y, whose values will produce (5/4)w for 3 days of work.
3(1/6+1/4)=>5/4>Option (E) gives this value so correct answer is (E)>12.



Intern
Joined: 21 Mar 2014
Posts: 2

Re: Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
20 Oct 2014, 09:39
Hi,
I am new here and I have solved this math correctly. However, here's my problem:
If I consider the number of days required to produce 'W' widgets as 'X' and 'X2' for X and Y respectively, I end up with the equation 5t^2  34t + 24 which yields me 2 solutions, one of which is correct (x=6)
However, when I take 'X' and 'Y' as 'X+2' and 'X', which are the same as above, because either ways, X is taking 2 days longer, I end up with the equation 5x^2  14x  24 which has no solutions (I hope I'm not making some stupid mistake here)
Can someone please clarify this and correct me where I'm wrong.



SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1825
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)

Re: Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
20 Oct 2014, 19:34
muhtasimhassan wrote: Hi,
I am new here and I have solved this math correctly. However, here's my problem:
If I consider the number of days required to produce 'W' widgets as 'X' and 'X2' for X and Y respectively, I end up with the equation 5t^2  34t + 24 which yields me 2 solutions, one of which is correct (x=6)
However, when I take 'X' and 'Y' as 'X+2' and 'X', which are the same as above, because either ways, X is taking 2 days longer, I end up with the equation 5x^2  14x  24 which has no solutions (I hope I'm not making some stupid mistake here)
Can someone please clarify this and correct me where I'm wrong. Refer my post above; I did in the same way..... As far as solving the equation, refer below..... \(5x^2  14x  24 = 0\) \(5x^2  20x + 6x  24 = 0\) \(5x(x4) + 6(x4) = 0\) (x4)(5x+6) = 0 x = 4 (Ignore the ve equation) x+2 = 6
_________________
Kindly press "+1 Kudos" to appreciate



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8659
Location: Pune, India

Re: Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
20 Oct 2014, 20:20
muhtasimhassan wrote: Hi,
I am new here and I have solved this math correctly. However, here's my problem:
If I consider the number of days required to produce 'W' widgets as 'X' and 'X2' for X and Y respectively, I end up with the equation 5t^2  34t + 24 which yields me 2 solutions, one of which is correct (x=6)
However, when I take 'X' and 'Y' as 'X+2' and 'X', which are the same as above, because either ways, X is taking 2 days longer, I end up with the equation 5x^2  14x  24 which has no solutions (I hope I'm not making some stupid mistake here)
Can someone please clarify this and correct me where I'm wrong. It doesn't matter whether you take the number of days as Days taken by machine X = X and Days taken by machine Y = X2 or Days taken by machine X = X+2 Days taken by machine Y = X Either way, you will get one valid value for X and you will need to manipulate that to get your answer. You need to find the number of days that will be taken by machine X to make 2w widgets. In first case, you get the equation as \(5X^2  34X + 24 = 0\) and get X = 6 as the only valid value (X = 4/5 gives X2 as negative but number of days cannot be negative). Machine X takes X days i.e. 6 days to make w widgets. So it will take 12 days to make 2w widgets. In the second case, you get \(5x^2  14x  24 = 0\) which is \(5x^2  20x + 6x  24 = 0\) 5x(x  4) + 6(x  4) = 0 (x4)(5x + 6) = 0 x = 4 This is the number of days taken by machine Y to make w widgets. So machine X takes 4+2 = 6 days to make w widgets. It will take 12 days to make 2w widgets. Either way, your answer will be the same.
_________________
[b]Karishma Veritas Prep GMAT Instructor
Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >



Intern
Joined: 21 Mar 2014
Posts: 2

Re: Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
20 Oct 2014, 20:39
PareshGmatVeritasPrepKarishmaThanks a lot. Careless of me to not have noticed such a simple solution to the equation 5x^2  14x  24 = 0



Current Student
Joined: 23 May 2013
Posts: 188
Location: United States
Concentration: Technology, Healthcare
GPA: 3.5

Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
08 Dec 2014, 07:30
VeritasPrepKarishma wrote: muhtasimhassan wrote: Hi,
I am new here and I have solved this math correctly. However, here's my problem:
If I consider the number of days required to produce 'W' widgets as 'X' and 'X2' for X and Y respectively, I end up with the equation 5t^2  34t + 24 which yields me 2 solutions, one of which is correct (x=6)
However, when I take 'X' and 'Y' as 'X+2' and 'X', which are the same as above, because either ways, X is taking 2 days longer, I end up with the equation 5x^2  14x  24 which has no solutions (I hope I'm not making some stupid mistake here)
Can someone please clarify this and correct me where I'm wrong. It doesn't matter whether you take the number of days as Days taken by machine X = X and Days taken by machine Y = X2 or Days taken by machine X = X+2 Days taken by machine Y = X Either way, you will get one valid value for X and you will need to manipulate that to get your answer. You need to find the number of days that will be taken by machine X to make 2w widgets. In first case, you get the equation as \(5X^2  34X + 24 = 0\) and get X = 6 as the only valid value (X = 4/5 gives X2 as negative but number of days cannot be negative). Machine X takes X days i.e. 6 days to make w widgets. So it will take 12 days to make 2w widgets. In the second case, you get \(5x^2  14x  24 = 0\) which is \(5x^2  20x + 6x  24 = 0\) 5x(x  4) + 6(x  4) = 0 (x4)(5x + 6) = 0 x = 4 This is the number of days taken by machine Y to make w widgets. So machine X takes 4+2 = 6 days to make w widgets. It will take 12 days to make 2w widgets. Either way, your answer will be the same. Just wanted to point out that this problem can be solved quite easily without solving a quadratic. Our equation for x is given by: \(\frac{1}{x} + \frac{1}{x2} = \frac{5}{12}\). \(\frac{x2 + x} {x(x2)} = \frac{5}{12}\). \(\frac{2x2}{x(x2)} = \frac{5}{12}\). \(\frac{2(x1)}{x(x2)} = \frac{5}{12}\). \(\frac{(x1)}{x(x2)} = \frac{5}{24}\). We see immediately that by letting \(x=6\) we find our solution of x. Therefore, since we're looking for the value of 2x, we see that the answer must be 12. Answer: E



Manager
Joined: 26 Feb 2015
Posts: 115

Re: Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
26 Mar 2015, 00:59
Bunuel wrote: SOLUTION
Running at their respective constant rates, Machine X takes 2 days longer to produce w widgets than Machine Y. At these rates, if the two machines together produce (5/4)w widgets in 3 days, how many days would it take Machine X alone to produce 2w widgets?
(A) 4 (B) 6 (C) 8 (D) 10 (E) 12
Any questions similar to this one somewhere? The regular Rate problems are quite easy, but as soon as they start mixing it up, adding variables, I'm clueless as to how to approach things.



Math Expert
Joined: 02 Sep 2009
Posts: 51099

Re: Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
26 Mar 2015, 03:08



Director
Joined: 07 Aug 2011
Posts: 538
Concentration: International Business, Technology

Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
26 Mar 2015, 03:49
MensaNumber wrote: Alternate Solution without algebra using POE.
If it takes 3 days to produce 5/4 widgets, it will take 3*(4/5) = 12/5 days to produce 1 widget.
If two machines were working at the same rate it would take, 2*12/5 i.e. approx 5 days days for x to produce 1 widget. Since machine X is slower it will take more than 5 days to produce 1 widget and subsequently more than 10 days to produce 2 widgets. The only answer more than 10 is 12 days. Answer E +1 Kudos !! Have a doubt , why did you discount 'w' while calculating time require to produce 1 widget ? If it takes 3 days to produce 5/4 widgets, it will take 3*(4/5) = 12/5 days to produce 1 widget. shldn't it be \(\frac{12}{5w}\) ?
_________________
Thanks, Lucky
_______________________________________________________ Kindly press the to appreciate my post !!



Manager
Joined: 26 Dec 2011
Posts: 114

Re: Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
10 May 2015, 03:48
Lucky2783 wrote: MensaNumber wrote: Alternate Solution without algebra using POE.
If it takes 3 days to produce 5/4 widgets, it will take 3*(4/5) = 12/5 days to produce 1 widget.
If two machines were working at the same rate it would take, 2*12/5 i.e. approx 5 days days for x to produce 1 widget. Since machine X is slower it will take more than 5 days to produce 1 widget and subsequently more than 10 days to produce 2 widgets. The only answer more than 10 is 12 days. Answer E +1 Kudos !! Have a doubt , why did you discount 'w' while calculating time require to produce 1 widget ? If it takes 3 days to produce 5/4 widgets, it will take 3*(4/5) = 12/5 days to produce 1 widget. shldn't it be \(\frac{12}{5w}\) ? Hi, Correction  If it takes 3 days to produce 5/4 widgets, it will take 1/3*(4/5) = 4/15 days to produce 1 widget. Thanks
_________________
Thanks, Kudos Please



Intern
Joined: 23 Jul 2015
Posts: 34

Re: Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
26 Jul 2015, 18:32
can someone pelase explain how they got from (1/t) + (1/((t2)) = 5/12 TO 5t^234t+24=0



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

Re: Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
26 Jul 2015, 18:48
jasonfodor wrote: can someone pelase explain how they got from (1/t) + (1/((t2)) = 5/12 TO 5t^234t+24=0 \(\frac{1}{t} + \frac{1}{t2} = \frac{5}{12}\) \(\frac{2t2}{t*(t2)} =\frac{5}{12}\) Cross multiplying and rearranging terms, you get , \(5t^234t+24= 0\) Hope it helps.



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8659
Location: Pune, India

Running at their respective constant rates, Machine X takes
[#permalink]
Show Tags
26 Jul 2015, 20:36
jasonfodor wrote: can someone pelase explain how they got from (1/t) + (1/((t2)) = 5/12 TO 5t^234t+24=0 You can also give the quadratic route a miss. Once you get (1/t) + (1/(t2)) = 5/12, you can try out some values for t. t is an integer since it is one of the given 5 options. To get 12 in denominator on the right hand side, t*(t2) should give you 12 or a multiple. 12 = 4*3 or 6*2 (not of the form t*(t2)) 24 = 6*4 (this is possible) Check 1/6 + 1/4 = 10/24 = 5/12 You get the value of t. Or you can also try substituting the value of t from each option.
_________________
[b]Karishma Veritas Prep GMAT Instructor
Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >




Running at their respective constant rates, Machine X takes &nbs
[#permalink]
26 Jul 2015, 20:36



Go to page
1 2
Next
[ 30 posts ]



