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.
Sep 0201:00 PM EDT
-11:59 PM EDT
Take 30% off all study plans with code COURSEWORK - Expires on Monday 9/7
Sep 0410:00 AM EDT
-11:59 PM EDT
We’ve worked incredibly hard to build TTP into the best test prep experience possible, and it would mean a lot to us to win Newsweek’s 2026 Readers’ Choice Award for Best Test Prep. If TTP has helped you, we’d be incredibly grateful for your vote.
Sep 0712:01 AM PDT
-11:59 PM PDT
On the 7th, GMAT Club Tests will be Free! Including all the Quizzes, Questions, and Tests. 12 AM - 11:59 PM PDT- Sep 07
10:00 AM PDT
-11:00 AM PDT
A complete walkthrough of GMAT Club’s free 12-week GMAT study plan: what you study each week, how progress and goals are tracked, how the error log works, and how your practice unlocks paid tools at no cost. - Sep 09
07:00 AM PDT
-10:00 AM PDT
Meet AdComs and explore top Master’s programs - MiM, MiF, MSc, MSBA and more. - Application Fee Waivers - Free 1-Week of GMAT Club Tests: - Master's Application Toolkit - Grand Prize Giveaway - Sep 09
10:00 AM PDT
-11:00 AM PDT
Three MBA applications. Three rejections. No interview invites. A year later, Aman was admitted to Cambridge Judge, SMU, and IMD. In this episode of MBA Admit Stories, Aman shares how he rebuilt his MBA application... 
Sep 1507:00 PM EDT
-09:00 PM EST
Elite scores are possible when you enroll in a powerful GMAT course, taught live online + 6 months access to TTP OnDemand video courses included! Class starts Tues/Thurs Sept. 15, 2026 - Nov. 15, 2027, 7:00pm-9:00pm EST
Sep 2108:00 PM EDT
-10:00 PM EDT
Boost your GMAT score in less than one month in a live online class + 6 months access to TTP OnDemand video courses included! Class starts Mon, Tues, Wed, Thur, Fri Sept. 21, 2026 - Oct. 9, 2027, 7:00pm-10:00pm EST
30 Oct 2019, 21:56
Kudos
Bookmarks
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
45%
(medium)
Question Stats:
65% (01:37) correct
35%
(01:35)
wrong
based on 110
sessions
History
Date
Time
Result
Not Attempted Yet
If the average (arithmetic mean) of x and y is positive, is x positive?
(1) xy < 0
(2) x = y + 4
(1) xy < 0
(2) x = y + 4
Updated on: 17 May 2021, 08:30
Originally posted by BrentGMATPrepNow on 31 Oct 2019, 14:14.
Last edited by BrentGMATPrepNow on 17 May 2021, 08:30, edited 1 time in total.
Last edited by BrentGMATPrepNow on 17 May 2021, 08:30, edited 1 time in total.
Kudos
Bookmarks
Bunuel
Given: The average (arithmetic mean) of x and y is positive
Target question: Is x positive?
Statement 1: xy < 0
This statement doesn't feel sufficient, so I'll TEST some values
There are several values of x and y that satisfy statement 1 (AND the given information). Here are two:
Case a: x = 3 and y = -1. In this case, the answer to the target question is YES, x is positive
Case b: x = -1 and y = 3. In this case, the answer to the target question is NO, x not is positive
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: x = y + 4
Rewrite as: y = x - 4
Since the average of x and y is positive, we can write: \(\frac{x+y}{2}>0\)
Replace y with x - 4 to get: \(\frac{x+(x-4)}{2}>0\)
Simplify numerator to get: \(\frac{2x-4}{2}>0\)
Simplify to get: \(x-2>0\)
Add 2 to both sides to get: \(x>2\)
If x is greater than 2, then x must be positive
The answer to the target question is YES, x is positive
Since we can answer the target question with certainty, statement 2 is SUFFICIENT
Answer: B
Cheers,
Brent
RELATED VIDEO
01 Nov 2019, 07:38
Kudos
Bookmarks
Bunuel
Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.
Visit https://www.mathrevolution.com/gmat/lesson for details.
The first step of the VA (Variable Approach) method is to modify the original condition and the question. We then recheck the question. We should simplify conditions if necessary.
The original condition means (x + y)/2 > 0 or x+y>0.
Since we have 2 variable (x and y) and 1 equations, D is most likely to be the answer. So, we should consider each condition on its own first. When a question is an inequality, inequalities should be counted as equations.
Condition 1)
If x = 1 and y = -1, then x is positive and the answer is 'yes'.
If x = -1 and y = 1, then x is negative and the answer is 'no'.
Since condition 1) does not yield a unique solution, it is not sufficient
Condition 2)
Since x + y > 0 and y = x - 4, then we have 2x - 4 > 0 or x > 2.
Thus x is positive and the answer is 'yes'.
Since condition 2) yields a unique solution, it is sufficient
Therefore, B is the answer.
If the original condition includes “1 variable”, or “2 variables and 1 equation”, or “3 variables and 2 equations” etc., one more equation is required to answer the question. If each of conditions 1) and 2) provide an additional equation, there is a 59% chance that D is the answer, a 38% chance that A or B is the answer, and a 3% chance that the answer is C or E. Thus, answer D (conditions 1) and 2), when applied separately, are sufficient to answer the question) is most likely, but there may be cases where the answer is A,B,C or E.
