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Difference between revisions of "2013 CEMC Gauss (Grade 8) Problems/Problem 5"

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{{CEMC box|year=2013|competition=Gauss (Grade 8)|num-b=4|num-a=6}}

Latest revision as of 20:47, 18 October 2025

Problem

Jarek multiplies a number by $3$ and gets an answer of $90$. If instead, he divides the number by $3$, what answer does he get?

$\textbf{(A)}\ 5 \qquad\textbf{(B)}\ 10 \qquad\textbf{(C)}\ 30 \qquad\textbf{(D)}\ 60 \qquad\textbf{(E)}\ 270$

Solution 1

Let $x$ be the number that Jarek multiplied by $3$. Using the first sentence, we have:

$3x = 90$

$x = 30$

We are then looking for $x \div 3$, which is $30 \div 3 = \boxed {\textbf {(B) } 10}$

~anabel.disher

Solution 2

Without finding the number that Jarek multiplied by $3$, we can note that $x \div 3 = 3x \div 9$. Thus, we can divide the product by $9$:

$90 \div 9 = \boxed {\textbf {(B) } 10}$

~anabel.disher

2013 CEMC Gauss (Grade 8) (ProblemsAnswer KeyResources)
Preceded by
Problem 4
Followed by
Problem 6
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CEMC Gauss (Grade 8)