Question 171 in the DS section of the OG
What is the value of (2T+T-X)/(T-X)
(1) (2T)/(T-X)=3
(2) (T-X)=5
The answer key simplifies statement 1 to (2T)/(T-X) + (T-X)/(T-X)
How is it that the equation is simplified to the equation above? I simplified it as (2T)/(T-X) + (T)/(T-X) - (X)/(T-X)
What am I missing?
DS Question Help - OG
This topic has expert replies
- theCodeToGMAT
- Legendary Member
- Posts: 1556
- Joined: Tue Aug 14, 2012 11:18 pm
- Thanked: 448 times
- Followed by:34 members
- GMAT Score:650
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
To find value of: ( 2T + T - X ) / ( T - X)
Rephrase: To find value of 2T/(T-X) + 1
Statement 1:
2T/(T-X) = 3
3 + 1 = 4
SUFFICIENT
Statement 2:
T-X = 5
INSUFFICIENT
Answer [spoiler]{A}[/spoiler]
Rephrase: To find value of 2T/(T-X) + 1
Statement 1:
2T/(T-X) = 3
3 + 1 = 4
SUFFICIENT
Statement 2:
T-X = 5
INSUFFICIENT
Answer [spoiler]{A}[/spoiler]
R A H U L
- theCodeToGMAT
- Legendary Member
- Posts: 1556
- Joined: Tue Aug 14, 2012 11:18 pm
- Thanked: 448 times
- Followed by:34 members
- GMAT Score:650
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
Steven, you over simplied the question, making it more complex.stevennu wrote:Question 171 in the DS section of the OG
What is the value of (2T+T-X)/(T-X)
(1) (2T)/(T-X)=3
(2) (T-X)=5
The answer key simplifies statement 1 to (2T)/(T-X) + (T-X)/(T-X)
How is it that the equation is simplified to the equation above? I simplified it as (2T)/(T-X) + (T)/(T-X) - (X)/(T-X)
What am I missing?
Rather than writing, (T-X)/(T-X) as T/(T-X) - X/(T-X
you could have simply written "1"
However, you din't make any mistake though.. If you simplify statement 1, then you will get some relation between T & X and most probably you will end up getting a definite numerical value
R A H U L
- GMATGuruNY
- GMAT Instructor
- Posts: 15539
- Joined: Tue May 25, 2010 12:04 pm
- Location: New York, NY
- Thanked: 13060 times
- Followed by:1906 members
- GMAT Score:790
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
An alternate approach is to simplify the statements and TEST TWO CASES.stevennu wrote:What is the value of (2t+t-x)/(t-x)?
(1) (2t)/(t-x) = 3
(2) t-x = 5
Statement 1: (2t)/(t-x) = 3
2t = 3t - 3x
3x = t.
If x=1 and t=3, then (2t+t-x)/(t-x) = (2*3 + 3 - 1)/(3-1) = 8/2 = 4.
If x=2 and t=6, then (2t+t-x)/(t-x) = (2*6 + 6 - 2)/(6-2) = 16/4 = 4.
Since (2t+t-x)/(t-x) = 4 in each case, SUFFICIENT.
Statement 2: t-x = 5
t = x+5.
If x=1 and t=6, then (2t+t-x)/(t-x) = (2*6 + 6 - 1)/(6-1) = 17/5.
If x=2 and t=7, then (2t+t-x)/(t-x) = (2*7 + 7 - 2)/(7-2) = 19/5.
Since (2t+t-x)/(t-x) can be equal to different values, INSUFFICIENT.
The correct answer is A.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
-
- Senior | Next Rank: 100 Posts
- Posts: 54
- Joined: Sat May 18, 2013 10:24 am
- Thanked: 1 times
- Followed by:1 members
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
I'm having trouble understanding why Statement 1 simplifies to (2T)/(T-X) + (T-X)/(T-X). Wouldn't you take each individual term and then write it above a common denominator? That's what I did when I simplified Statement 1 to (2T)/(T-X) + (T)/(T-X) - (X)/(T-X). I took each of the terms in the numerator and wrote them above the common denominator of (T-X). What rule or further simplification allows us to go from Statement 1 to (2T)/(T-X) + (T-X)/(T-X)? Why aren't the T and -X broken out?theCodeToGMAT wrote:Steven, you over simplied the question, making it more complex.stevennu wrote:Question 171 in the DS section of the OG
What is the value of (2T+T-X)/(T-X)
(1) (2T)/(T-X)=3
(2) (T-X)=5
The answer key simplifies statement 1 to (2T)/(T-X) + (T-X)/(T-X)
How is it that the equation is simplified to the equation above? I simplified it as (2T)/(T-X) + (T)/(T-X) - (X)/(T-X)
What am I missing?
Rather than writing, (T-X)/(T-X) as T/(T-X) - X/(T-X
you could have simply written "1"
However, you din't make any mistake though.. If you simplify statement 1, then you will get some relation between T & X and most probably you will end up getting a definite numerical value
I understand the T-X / T-X is great because you can simplify it to 1, however I'm not sure how they arrived at that statement.
Thanks for the replies!
-
- Senior | Next Rank: 100 Posts
- Posts: 54
- Joined: Sat May 18, 2013 10:24 am
- Thanked: 1 times
- Followed by:1 members
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
I'm having trouble understanding why Statement 1 simplifies to (2T)/(T-X) + (T-X)/(T-X). Wouldn't you take each individual term and then write it above a common denominator? That's what I did when I simplified Statement 1 to (2T)/(T-X) + (T)/(T-X) - (X)/(T-X). I took each of the terms in the numerator and wrote them above the common denominator of (T-X). What rule or further simplification allows us to go from Statement 1 to (2T)/(T-X) + (T-X)/(T-X)? Why aren't the T and -X broken out?theCodeToGMAT wrote:Steven, you over simplied the question, making it more complex.stevennu wrote:Question 171 in the DS section of the OG
What is the value of (2T+T-X)/(T-X)
(1) (2T)/(T-X)=3
(2) (T-X)=5
The answer key simplifies statement 1 to (2T)/(T-X) + (T-X)/(T-X)
How is it that the equation is simplified to the equation above? I simplified it as (2T)/(T-X) + (T)/(T-X) - (X)/(T-X)
What am I missing?
Rather than writing, (T-X)/(T-X) as T/(T-X) - X/(T-X
you could have simply written "1"
However, you din't make any mistake though.. If you simplify statement 1, then you will get some relation between T & X and most probably you will end up getting a definite numerical value
I understand the T-X / T-X is great because you can simplify it to 1, however I'm not sure how they arrived at that statement.
Thanks for the replies!
- theCodeToGMAT
- Legendary Member
- Posts: 1556
- Joined: Tue Aug 14, 2012 11:18 pm
- Thanked: 448 times
- Followed by:34 members
- GMAT Score:650
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
Well Steven... that depends upon how you break a question.
For instance: recently a question was posted in which we had to find whether r^5s^3t^4 <0
Now, there are two(or more) ways of looking this problem.
Some solved using what has to be found i.e. r^5s^3t^4
Some simplified to rs < 0 .. since even power of -ve is +ve.
So, there is no such rule for Simplification.. maybe one tick works well for one .. may not work well for other
For instance: recently a question was posted in which we had to find whether r^5s^3t^4 <0
Now, there are two(or more) ways of looking this problem.
Some solved using what has to be found i.e. r^5s^3t^4
Some simplified to rs < 0 .. since even power of -ve is +ve.
So, there is no such rule for Simplification.. maybe one tick works well for one .. may not work well for other
R A H U L
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
I think stevennu meant to say that the expression in the target question (not statement 1) simplifies to be (2T)/(T-X) + (T-X)/(T-X)stevennu wrote:I'm having trouble understanding why Statement 1 simplifies to (2T)/(T-X) + (T-X)/(T-X). Wouldn't you take each individual term and then write it above a common denominator? That's what I did when I simplified Statement 1 to (2T)/(T-X) + (T)/(T-X) - (X)/(T-X). I took each of the terms in the numerator and wrote them above the common denominator of (T-X). What rule or further simplification allows us to go from Statement 1 to (2T)/(T-X) + (T-X)/(T-X)? Why aren't the T and -X broken out?theCodeToGMAT wrote:Steven, you over simplied the question, making it more complex.stevennu wrote:Question 171 in the DS section of the OG
What is the value of (2T+T-X)/(T-X)
(1) (2T)/(T-X)=3
(2) (T-X)=5
The answer key simplifies statement 1 to (2T)/(T-X) + (T-X)/(T-X)
How is it that the equation is simplified to the equation above? I simplified it as (2T)/(T-X) + (T)/(T-X) - (X)/(T-X)
What am I missing?
Rather than writing, (T-X)/(T-X) as T/(T-X) - X/(T-X
you could have simply written "1"
However, you din't make any mistake though.. If you simplify statement 1, then you will get some relation between T & X and most probably you will end up getting a definite numerical value
I understand the T-X / T-X is great because you can simplify it to 1, however I'm not sure how they arrived at that statement.
Thanks for the replies!
There's a nice rule that says (a+b)/c = a/c + b/c
So, (2T+T-X)/(T-X) = 2T/(T-X) + (T-X)/(T-X)
= 2T/(T-X) + 1
Cheers,
Brent
- theCodeToGMAT
- Legendary Member
- Posts: 1556
- Joined: Tue Aug 14, 2012 11:18 pm
- Thanked: 448 times
- Followed by:34 members
- GMAT Score:650
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
To reach from Statement 1 to what question is asking :
(2T)/(T-X)=3
Add 1 both sides
(2T)/(T-X) + 1 = 3 + 1 --(1)
Since, "1" can be re-written as (T-X)/(T-X) --(2)
replace "1" in LHS of (1) with (2)
(2T)/(T-X) + (T-X)/(T-X) = 4
Hope this clears!
(2T)/(T-X)=3
Add 1 both sides
(2T)/(T-X) + 1 = 3 + 1 --(1)
Since, "1" can be re-written as (T-X)/(T-X) --(2)
replace "1" in LHS of (1) with (2)
(2T)/(T-X) + (T-X)/(T-X) = 4
Hope this clears!
R A H U L
-
- Senior | Next Rank: 100 Posts
- Posts: 54
- Joined: Sat May 18, 2013 10:24 am
- Thanked: 1 times
- Followed by:1 members
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
I think I was making an error with the simplification. After breaking up the terms of the numerator to 2T/T-X + T/T-X - X/T-X, I started to cancel the T/T in each of the equations. I just realized that since the two terms T/T-X and X/T-X have the same common denominator, I should have just simplified to T-X/T-X. However, my question is why couldn't we simplify T/T-X to 1/-X and -X/T-X to 1/T? Don't the T's and X's cancel?
- theCodeToGMAT
- Legendary Member
- Posts: 1556
- Joined: Tue Aug 14, 2012 11:18 pm
- Thanked: 448 times
- Followed by:34 members
- GMAT Score:650
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
Steven, you cannot do that..
That property works fine when performing such operation with numerator but not with denominator
For instance:
If the question were: 2T/T-X + (T-X)/T - (T-X)/T
then you could have simplified to: 2T/T-X + T/T - X/T - T/T + X/T
That property works fine when performing such operation with numerator but not with denominator
For instance:
If the question were: 2T/T-X + (T-X)/T - (T-X)/T
then you could have simplified to: 2T/T-X + T/T - X/T - T/T + X/T
R A H U L
- Johnniewales
- Newbie | Next Rank: 10 Posts
- Posts: 6
- Joined: Wed Jul 15, 2015 5:39 am
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
Why can't we say t=5+x and substitute for T in the equation
. Please can someone tell me why because if I choose to go that route
Statement 2 also seems sufficient
. Please can someone tell me why because if I choose to go that route
Statement 2 also seems sufficient
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
\Johnniewales wrote:Why can't we say t=5+x and substitute for T in the equation
. Please can someone tell me why because if I choose to go that route
Statement 2 also seems sufficient
Show us your work when you replaced t with 5+x
Cheers,
Brent