GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 09 Dec 2018, 16:03

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

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Events & Promotions

Events & Promotions in December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
• Free GMAT Algebra Webinar

December 09, 2018

December 09, 2018

07:00 AM PST

09:00 AM PST

Attend this Free Algebra Webinar and learn how to master Inequalities and Absolute Value problems on GMAT.
• Free lesson on number properties

December 10, 2018

December 10, 2018

10:00 PM PST

11:00 PM PST

Practice the one most important Quant section - Integer properties, and rapidly improve your skills.

If the average (arithmetic mean) of 3 integers x, y, z is 10, what is

Author Message
TAGS:

Hide Tags

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 6605
GMAT 1: 760 Q51 V42
GPA: 3.82
If the average (arithmetic mean) of 3 integers x, y, z is 10, what is  [#permalink]

Show Tags

14 Aug 2018, 16:45
00:00

Difficulty:

25% (medium)

Question Stats:

67% (00:48) correct 33% (00:47) wrong based on 42 sessions

HideShow timer Statistics

[Math Revolution GMAT math practice question]

If the average (arithmetic mean) of 3 integers x, y, z is 10, what is the value of z?

1) x=1
2) x=5-y

_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $99 for 3 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Math Expert Joined: 02 Aug 2009 Posts: 7095 Re: If the average (arithmetic mean) of 3 integers x, y, z is 10, what is [#permalink] Show Tags 14 Aug 2018, 18:57 MathRevolution wrote: [Math Revolution GMAT math practice question] If the average (arithmetic mean) of 3 integers x, y, z is 10, what is the value of z? 1) x=1 2) x=5-y So x+y+z=30......z=? 1) x=1.. y+z=29... Insufficient 2) x=5-y x+y=5.. So z=30-5=25 Sufficient B _________________ 1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372 2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html 3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html GMAT online Tutor Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 6605 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: If the average (arithmetic mean) of 3 integers x, y, z is 10, what is [#permalink] Show Tags 15 Aug 2018, 06:45 => 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. The first step of the VA (Variable Approach) method is to modify the original condition and the question. We then recheck the question. The original condition gives $$\frac{( x + y + z )}{3} = 10$$ or $$x + y + z = 30$$. Rearranging yields $$z = 30 – ( x + y ).$$ Condition 2) gives $$x + y = 5$$, so condition 2) is sufficient . Condition 1) is not sufficient since it gives no information about the value of y. Therefore, B is the answer. Answer: B _________________ MathRevolution: Finish GMAT Quant Section with 10 minutes to spare The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. "Only$99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Senior Manager
Joined: 07 Jul 2012
Posts: 378
Location: India
Concentration: Finance, Accounting
GPA: 3.5
Re: If the average (arithmetic mean) of 3 integers x, y, z is 10, what is  [#permalink]

Show Tags

15 Aug 2018, 08:26
Given: $$\frac{x+y+z}{3}$$= 10; x+y+z=30

1) x=1. No inf of y. So z cannot be calculated.[Insuff]

2) x= 5-y; x+y=5; Put this value in original equation above. Value of z can be found [Suff]

_________________

Kindly hit kudos if my post helps!

Re: If the average (arithmetic mean) of 3 integers x, y, z is 10, what is &nbs [#permalink] 15 Aug 2018, 08:26
Display posts from previous: Sort by