Last visit was: 26 Dec 2024, 04:58 It is currently 26 Dec 2024, 04:58
Decision Tracker
My Rewards
New comers' posts
New posts
Unanswered

Close

GRE Prep 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
Your Progress

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

Practice
Pays

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Go to My Error Log Learn more
Close

Request Expert Reply

Confirm Cancel
PREVIOUS TOPIC
NEXT TOPIC

If the average (arithmetic mean) of x2 and y2 is 47, and xy = 3, what

Tags :
Find Similar Topics  About  Add a Tag

Show Tags
Hide Tags

User avatar
D
Carcass
Verbal Expert
Joined: 18 Apr 2015
Posts: 30507
Own Kudos [?]: 36860 [3]
Given Kudos: 26108
Send PM
If the average (arithmetic mean) of x2 and y2 is 47, and xy = 3, what [#permalink] New post   27 Dec 2021, 12:53
Expert Reply
3
Bookmarks
00:00

Question Stats:

92% (01:54) correct 7% (03:48) wrong based on 13 sessions

Hide Show timer Statistics

If the average (arithmetic mean) of \(x^2\) and \(y^2\) is 47, and xy = 3, what is the average of the positive values of x and y?


(A) 1.5
(B) 3
(C) 5
(D) 10
(E) 15
ShowHide Answer
Official Answer
C
User avatar
G
BrushMyQuant
Moderator
Moderator
Joined: 02 Jan 2020
Status:GRE Quant Tutor
Posts: 1115
Own Kudos [?]: 974 [1]
Given Kudos: 9
Location: India
Concentration: General Management
Schools: XLRI Jamshedpur, India - Class of 2014
GMAT 1: 700 Q51 V31
GPA: 2.8
WE:Engineering (Computer Software)
Send PM
Re: If the average (arithmetic mean) of x2 and y2 is 47, and xy = 3, what [#permalink] New post   27 Dec 2021, 20:49
1
Given that Average of \(x^2\) and \(y^2\) is 47 and xy = 3 and we need to find the average of x and y

Theory: Average = \(\frac{Sum Of All The Numbers In The Set }{ Total Number Of Numbers In The Set}\)

Average of x and y = \(\frac{x+y }{ 2}\)

Average of \(x^2\) and \(y^2\) = \(\frac{x^2 + y^2 }{ 2}\) = 47
=> \(x^2 + y^2\) = 47*2 = 94
and xy = 3

Now, we know that \((x+y)^2 = x^2 + y^2 + 2xy \)
=> \((x+y)^2\) = 94 + 2*3 = 94 + 6 = 100
=> x + y = \(\sqrt{100}\) = 10 (as we are asked about the positive values of x and y)
=> Average of x and y = \(\frac{x+y }{ 2}\) = \(\frac{10}{2}\) = 5

So, Answer will be C
Hope it helps!

Watch the following video to Learn the Basics of Statistics

User avatar
bumpbot
GRE Prep Club Legend
GRE Prep Club Legend
Joined: 07 Jan 2021
Posts: 5091
Own Kudos [?]: 76 [0]
Given Kudos: 0
Send PM
Re: If the average (arithmetic mean) of x2 and y2 is 47, and xy = 3, what [#permalink] New post   28 Oct 2023, 19:41
Hello from the GRE Prep Club BumpBot!

Thanks to another GRE Prep 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.
Prep Club for GRE Bot
gmatclubot
Re: If the average (arithmetic mean) of x2 and y2 is 47, and xy = 3, what [#permalink]
28 Oct 2023, 19:41
Moderators:
adewale223
GRE Instructor
88 posts
bronaugust
GRE Forum Moderator
37 posts
BrushMyQuant
Moderator
1115 posts
VibhuAnurag
GRE Instructor
234 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Main navigation

Partners

GRE Resources

www.ets.org/gre | About | Terms and Conditions and Privacy Policy | Prep Club for GRE Rules | Contact