help required

This topic has expert replies
Legendary Member
Posts: 512
Joined: Mon Jun 18, 2012 11:31 pm
Thanked: 42 times
Followed by:20 members

help required

by sana.noor » Sun May 12, 2013 3:53 am
If T is an integer between 10 and 100, what is the valueof T ?
(1) The positive difference between TÂ’ digits is 4.
(2) The sum of TÂ’ digits is 12.
OA is E but i guess it should be C. the official answer explians that T could be 48 or 84. but according to statement 1, the positive difference between T's digits is 4. it means it could only be 84 but not 48 because question says positive difference. please correct me if i am wrong.
Work hard in Silence, Let Success make the noise.

If you found my Post really helpful, then don't forget to click the Thank/follow me button. :)

User avatar
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

by GMATGuruNY » Sun May 12, 2013 5:25 am
sana.noor wrote:If T is an integer between 10 and 100, what is the valueof T ?
(1) The positive difference between TÂ’ digits is 4.
(2) The sum of TÂ’ digits is 12.
The POSITIVE DIFFERENCE between x and y = |x-y|.

Let x = the tens digit and y = the units digit.

Statement 1: |x-y| = 4.
It's possible that x=9 and y=5.
In this case, T=95.
It's possible that x=8 and y=4.
In this case, T=84.
Since different values for T are possible, INSUFFICIENT.

Statement 2: x+y = 12.
It's possible that x=8 and y=4.
In this case, T=84.
It's possible that x=9 and y=3.
In this case, T=93.
Since different values for T are possible, INSUFFICIENT.

Statements combined:
Statement 2 implies that x=12-y.
Substituting x=12-y into |x-y| = 4, we get:
|(12-y)-y| = 4
|12-2y| = 4.

Case 1: 12-2y = 4
-2y = -8
y=4, implying that x=8.
In this case, T = 84.

Case 2: -(12-2y) = 4
-12 + 2y = 4
2y = 16
y=8, implying that x=4.
In this case, T = 48.

Since different values for T are possible, INSUFFICIENT.

The correct answer is E.
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

GMAT/MBA Expert

User avatar
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

by Brent@GMATPrepNow » Sun May 12, 2013 5:31 am
Delete
Last edited by Brent@GMATPrepNow on Sun May 12, 2013 5:33 am, edited 1 time in total.
Brent Hanneson - Creator of GMATPrepNow.com
Image

GMAT/MBA Expert

User avatar
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

by Brent@GMATPrepNow » Sun May 12, 2013 5:32 am
sana.noor wrote:If T is an integer between 10 and 100, what is the value of T ?
(1) The positive difference between T's digits is 4.
(2) The sum of T's digits is 12.
OA is E but i guess it should be C. the official answer explians that T could be 48 or 84. but according to statement 1, the positive difference between T's digits is 4. it means it could only be 84 but not 48 because question says positive difference. please correct me if i am wrong.
The positive difference between T's digits is 4 means that one of the digits is 4 greater than the other. There's nothing to indicate which value (the tens digit or the ones digit) is greater.

So . . .

Target question: What is the value of T ?

Statements 1 and 2 combined:
Given both statements, it's still possible that T = 48 or T = 84.

Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer = E

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image