What is the average (arithmetic mean) of \(x\) and \(y?\)
(1) The average of \(x\) and \(2y\) is 10.
(2) The average of \(2x\) and \(7y\) is 32.
[spoiler]OA=C[/spoiler]
Source: Official Guide
What is the average (arithmetic mean) of \(x\) and \(y?\)
This topic has expert replies

 Legendary Member
 Posts: 1272
 Joined: 01 Mar 2018
 Followed by:2 members
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats

 Junior  Next Rank: 30 Posts
 Posts: 14
 Joined: 25 Jul 2020
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
To find the arithmetic mean of x and y we need values of x and y
St1: gives us one equation with 2 variables.
Not sufficient
St2 Same as st1
Taking both statements together: We have two equations and two variables. enough to find the value of x and Y
Hence sufficient
OA: C
St1: gives us one equation with 2 variables.
Not sufficient
St2 Same as st1
Taking both statements together: We have two equations and two variables. enough to find the value of x and Y
Hence sufficient
OA: C
GMAT/MBA Expert
 [email protected]
 GMAT Instructor
 Posts: 6353
 Joined: 25 Apr 2015
 Location: Los Angeles, CA
 Thanked: 43 times
 Followed by:25 members
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
Solution:Gmat_mission wrote: ↑Sat Aug 01, 2020 6:09 amWhat is the average (arithmetic mean) of \(x\) and \(y?\)
(1) The average of \(x\) and \(2y\) is 10.
(2) The average of \(2x\) and \(7y\) is 32.
[spoiler]OA=C[/spoiler]
Source: Official Guide
Question Stem Analysis:
We need to determine the average of x and y, i.e., the value of (x + y)/2. Notice that if we can determine the values of x and y, then we can determine the value of (x + y)/2.
Statement One Alone:
We are given that (x + 2y)/2 = 10. However, since we can’t determine either the value of x or of y, we can’t determine the value of (x + y)/2. Statement one alone is not sufficient.
Statement Two Alone:
We are given that (2x + 7y)/2 = 32. However, since we can’t determine either the value of x or of y, we can’t determine the value of (x + y)/2. Statement two alone is not sufficient.
Statements One and Two Together:
From the two statements, we have two linear equations in two variables. Note that neither equation is dependent on the other, which means that one equation is not a linear multiple of the other. Thus, we can solve for the values of x and y, and hence we can determine the value of (x + y)/2. Both statements are sufficient.
Answer: C
Scott WoodburyStewart
Founder and CEO
[email protected]
See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews
GMAT/MBA Expert
 [email protected]
 GMAT Instructor
 Posts: 6353
 Joined: 25 Apr 2015
 Location: Los Angeles, CA
 Thanked: 43 times
 Followed by:25 members
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
Solution:Gmat_mission wrote: ↑Sat Aug 01, 2020 6:09 amWhat is the average (arithmetic mean) of \(x\) and \(y?\)
(1) The average of \(x\) and \(2y\) is 10.
(2) The average of \(2x\) and \(7y\) is 32.
[spoiler]OA=C[/spoiler]
Source: Official Guide
Question Stem Analysis:
We need to determine the average of x and y, i.e., the value of (x + y)/2. Notice that if we can determine the values of x and y, then we can determine the value of (x + y)/2.
Statement One Alone:
We are given that (x + 2y)/2 = 10. However, since we can’t determine either the value of x or of y, we can’t determine the value of (x + y)/2. Statement one alone is not sufficient.
Statement Two Alone:
We are given that (2x + 7y)/2 = 32. However, since we can’t determine either the value of x or of y, we can’t determine the value of (x + y)/2. Statement two alone is not sufficient.
Statements One and Two Together:
From the two statements, we have two linear equations in two variables. Note that neither equation is dependent on the other, which means that one equation is not a linear multiple of the other. Thus, we can solve for the values of x and y, and hence we can determine the value of (x + y)/2. Both statements are sufficient.
Answer: C
Scott WoodburyStewart
Founder and CEO
[email protected]
See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews