Events & Promotions
|
|
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Apr 2711:00 AM EDT
-12:00 PM EDT
Prefer video-based learning? The Target Test Prep OnDemand course is a one-of-a-kind video masterclass featuring 400 hours of lecture-style teaching by Scott Woodbury-Stewart, founder of Target Test Prep and one of the most accomplished GMAT instructors
Apr 2808:00 AM PDT
-11:00 AM PDT
Whether you are just beginning your MBA journey or fine-tuning your path to a 700+ score, GMAT Day is designed to give you a competitive edge.
Apr 2912:30 AM EDT
-01:30 AM EDT
Learn how Kamakshi achieved a GMAT 675 with an impressive 96th %ile in Data Insights. Discover the unique methods and exam strategies that helped her excel in DI along with other sections for a balanced and high score.
Apr 3001:30 AM EDT
-02:30 AM EDT
At one point, she believed GMAT wasn’t for her. After scoring 595, self-doubt crept in and she questioned her potential. But instead of quitting, she made the right strategic changes. The result? A remarkable comeback to 695. Check out how Saakshi did it.
May 0111:00 AM PDT
-12:00 PM PDT
Free- full-length test + 15 concept videos + 150+ short videos + study plan!
May 0306:30 AM PDT
-08:30 AM PDT
Verbal trouble on GMAT? Fix it NOW! Join Sunita Singhvi for a focused webinar on actionable strategies to boost your Verbal score and take your performance to the next level.
28 Feb 2016, 09:22
Kudos
Bookmarks
A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
15%
(low)
Question Stats:
79% (01:23) correct
21%
(01:50)
wrong
based on 267
sessions
History
Date
Time
Result
Not Attempted Yet
If a and b are both two digit integers, is a + b a multiple of 11?
(1) The tens digit of a is equal to the units digit of b, and the tens digit of b is equal to the units digit of a
(2) Both a and b are odd
(1) The tens digit of a is equal to the units digit of b, and the tens digit of b is equal to the units digit of a
(2) Both a and b are odd
29 Feb 2016, 04:38
Kudos
Bookmarks
Bunuel
HI,
Info from Q--
A and b are 2-digit numbers
lets see the statements:-
(1) The tens digit of a is equal to the units digit of b, and the tens digit of b is equal to the units digit of a
Means xy = yx.. or
a=10x+y, then b=10y+x..
so a+b= 10x+y+10y+x=11x+11y..
Ans is YES a+b is div by 11
Suff
(2) Both a and b are odd
not much info to work on..
Insuff
A
29 Feb 2016, 20:46
Kudos
Bookmarks
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 and b are both two digit integers, is a + b a multiple of 11?
(1) The tens digit of a is equal to the units digit of b, and the tens digit of b is equal to the units digit of a
(2) Both a and b are odd
In the original condition, 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), they become a=10x+y=odd and b=10y+x=odd -> a+b=10x+y+10y+x=11(x+y), in which 11 is the factor. Thus, it is sufficient and C is the answer.
However, this is an integer question, which is one of the key questions. Apply the mistake type 4(A). Even just for 1), 11 is always the factor, which is yes and sufficient.
Thus, the answer is A.
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.
If a and b are both two digit integers, is a + b a multiple of 11?
(1) The tens digit of a is equal to the units digit of b, and the tens digit of b is equal to the units digit of a
(2) Both a and b are odd
In the original condition, 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), they become a=10x+y=odd and b=10y+x=odd -> a+b=10x+y+10y+x=11(x+y), in which 11 is the factor. Thus, it is sufficient and C is the answer.
However, this is an integer question, which is one of the key questions. Apply the mistake type 4(A). Even just for 1), 11 is always the factor, which is yes and sufficient.
Thus, the answer is A.
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.
