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$x, y, z$ are three numbers. The mean of $x, y, z$ is $3x$. What is the mean of $y$ and $z$?

Is the answer $4x$?

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If $\dfrac{x+y+z}{3}=3x$, then... – J. M. Oct 25 '11 at 16:10
up vote 10 down vote accepted

Yes. Simply write: $$ \frac{x+y+z}{3} = 3x\Rightarrow y+z = 8x\Rightarrow \frac{y+z}{2} = 4x. $$

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If the mean of three numbers is $3x$, then the sum of the numbers is $9x$. ...

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This answer is useful. – The Chaz 2.0 Oct 25 '11 at 16:46

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