Competition problem — Algebra — Maths Olympiad Prep

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Algebra Difficulty 1.5 Junior Find the answer

If $x=3$ , $y=2x$ , and $z=3y$ , what is the average of $x$ , $y$ , and $z$ ?

Your answer

A number or a short expression. Spacing and $ signs are ignored.

Solution

Since $x=3$ and $y=2x$ , then $y=2 \times 3=6$ . Since $y=6$ and $z=3y$ , then $z=3 \times 6=18$ . Therefore, the average of $x, y$ and $z$ is $\frac{x+y+z}{3}=\frac{3+6+18}{3}=9$ .

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