Question : j + k = ?

Statement 1: mj + mk = 2m
m (j + k) = 2m
i.e. m (j+k-2) = 0
i.e. either m = 0 OR j+k = 2
NOT SUFFICIENT

Statement 2: 5j + 5k = 10
i.e. 5(j +k) =10
i.e. j+k = 2
SUFFICIENT

Answer: Option
_________________

Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION

VERITAS PREP OFFICIAL SOLUTION

Solution: B.

While statement 1 may look sufficient at first, recognize that m could be 0 and the statement would be satisfied regardless of j and k. For example, j could be 9 and k could be 11, but if m is 0 the equation would be: 0(9) + 0(11) = 2(0). If m is not 0, then j + k must equal 2, as you could simply divide both sides by m to get j + k = 2. Because you can get multiple answers to the question, statement 1 is not sufficient.

Statement 2 is sufficient, as you can divide both sides by 5 to get j + k = 2. And remember to ask “Why Are You Here?” for statement 2. The fact that statement 2 is quite clearly sufficient should demonstrate to you that the difficulty in this question lies within statement 1. Statement 2 here is an invitation to go back and spend more time on statement 1 if you inadvertently just divided both sides by m and called it “sufficient”.
_________________

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?
Extra-hard Quant Tests with Brilliant Analytics

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources