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Bunuel
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What is the average (arithmetic mean) of x and y? 25 Mar 2015, 04:11
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C
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5% (low)

Question Stats:

89% (01:01) correct 11% (01:06) wrong based on 225 sessions

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What is the average (arithmetic mean) of x and y?

(1) The average (arithmetic mean) of x, y and k is 7.

(2) The average (arithmetic mean) of x, y and 3k is 13.
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C
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What is the average (arithmetic mean) of x and y? 25 Mar 2015, 07:21
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Bunuel
What is the average (arithmetic mean) of x and y?

(1) The average (arithmetic mean) of x, y and k is 7.

(2) The average (arithmetic mean) of x, y and 3k is 13.


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Reworded, (x+y)/2 =?

Statement 1 :
x+y=21-k
insufficient

Statement 2:
x + y = 39-3k
insufficient

Combined, we are able to find the value of k, which gives us a unique value for (x+y)/2
Sufficient

Answer : C
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What is the average (arithmetic mean) of x and y? 25 Mar 2015, 20:21
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Bunuel
What is the average (arithmetic mean) of x and y?

(1) The average (arithmetic mean) of x, y and k is 7.

(2) The average (arithmetic mean) of x, y and 3k is 13.


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(1) The average (arithmetic mean) of x, y and k is 7.
Insufficient, as X,Y could be -ive integers or fractions.

(2) The average (arithmetic mean) of x, y and 3k is 13.
Insufficient, as X,Y could be -ive integers or fractions.

Combined A/B
X+Y+K=7*3
X+Y+3K=39
we can solve for k and find X+Y/2 easily.
AnswerC
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What is the average (arithmetic mean) of x and y? 30 Mar 2015, 04:47
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Bunuel
What is the average (arithmetic mean) of x and y?

(1) The average (arithmetic mean) of x, y and k is 7.

(2) The average (arithmetic mean) of x, y and 3k is 13.


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MAGOOSH OFFICIAL SOLUTION:
Attachment:
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averageofxandy_text.png [ 33.78 KiB | Viewed 9986 times ]
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What is the average (arithmetic mean) of x and y? 30 Mar 2015, 04:49
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Hi ,
Average of x+y means (x+y)/2.
Statement 1 not sufficient:
Average of x , y and k is 7. That is (x+y+k) = 21.
We don’t know the value of k it is not sufficient.
Statement 2 not sufficient:
Average of x , y and 3k is 13. That is (x+y+3k) = 39.
We don’t know the value of k it is not sufficient.
Together it is sufficient.
We have two equations we can find the average of x+y.
So answer is C.
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What is the average (arithmetic mean) of x and y? 06 Aug 2015, 18:45
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I solved this problem from my assumption.
Step 1:I noted to find x+y/2
Step 2:After seeing Stat.1 and Stat 2, I figured it out that If I've found the value of "k" from that can bring me a value of x+y/2 definitely

Solution: Stat.1 says x+y+K=21 and Stat. 2 says x+y+3k=39 ,by subtraction these two equation we can find the value k=9 and putting the value of k to Stat.1 equation we can find x+y+k=21
or x+y+9=21
or x+y/2=15 and similarly from Stat.2 too.
Because of finding Value of K required two statements together,The Answer is C

Please advice me if my assumption is wrong
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What is the average (arithmetic mean) of x and y? 21 Dec 2016, 17:26
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Here is my solution to this one =>
We need the value of x+y to get the average = x+y/2

Statement 1=>
No clue of K ->not sufficient
Statement 2=>
No clue of K-> not sufficient

Combing the two statements =>K=9
Hence x+y=12
so mean = 6

Hence sufficient
Hence C
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What is the average (arithmetic mean) of x and y? 04 Sep 2021, 03:35
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X+Y/2=?

St1: (X+Y+K)/3=7 => X+Y+K=21 so now, if X+Y=A it will A+K=21 => A=21-K
St2: (X+Y+3K)/3=13 => X+Y+3K=39 now X+Y=A => A=21-K. So 21-K+3K=39 => 2K=18 => K=9
Now let's test:
St1: (X+Y+K)/3=7 => X+Y+9=21 => (X+Y)/2=(21-9)/2 => (X+Y)/2=6
St2: (X+Y+3K)/3=13 => X+Y+27=39 => (X+Y)/2=(39-27)/2 => (X+Y)/2=6

I think both sufficient. Answer is C.
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