## If the average (arithmetic mean) of $$x, y$$ and $$15$$ is $$9,$$ and the average of $$x, 2y$$ and $$2$$ is $$7,$$ then

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### If the average (arithmetic mean) of $$x, y$$ and $$15$$ is $$9,$$ and the average of $$x, 2y$$ and $$2$$ is $$7,$$ then

by M7MBA » Thu Oct 01, 2020 6:54 am

00:00

A

B

C

D

E

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If the average (arithmetic mean) of $$x, y$$ and $$15$$ is $$9,$$ and the average of $$x, 2y$$ and $$2$$ is $$7,$$ then $$y =$$

A. 5
B. 6
C. 7
D. 8
E. 9

Source: Magoosh

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### Re: If the average (arithmetic mean) of $$x, y$$ and $$15$$ is $$9,$$ and the average of $$x, 2y$$ and $$2$$ is $$7,$$ t

by psarma » Thu Oct 01, 2020 3:44 pm
Average of x,y & 15 is 9
i.e (x+y+15)/3 = 9
or x+y=12

Also, average of x,2y & 2 is 7
i.e (x+2y+2)/3 = 7
or x+2y = 19

Subtracting 1st equation from 2nd equation,
we get y = 7

Option C

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### Re: If the average (arithmetic mean) of $$x, y$$ and $$15$$ is $$9,$$ and the average of $$x, 2y$$ and $$2$$ is $$7,$$ t

by [email protected] » Tue Oct 06, 2020 3:15 am
M7MBA wrote:
Thu Oct 01, 2020 6:54 am
If the average (arithmetic mean) of $$x, y$$ and $$15$$ is $$9,$$ and the average of $$x, 2y$$ and $$2$$ is $$7,$$ then $$y =$$

A. 5
B. 6
C. 7
D. 8
E. 9

Solution:

We can create the equations:

(x + y + 15)/3 = 9

and

(x + 2y + 2)/3 = 7

Subtracting the first equation from the second, we have:

(y - 13)/3 = -2

y - 13 = -6

y = 7