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, 2019

Combinatorics Difficulty 1.2 Junior Find the answer Canada

Based on the graph shown, how many vehicles had an average speed of at least 80 km/h?

Pick one

Solution

When $x=3$ , $\begin{align*} 2x&=2\times3=6\\ 3x-1&=3\times3-1=8\\ x+5&=3+5=8\\ 7-x&=7-3=4\\ 6+2x&=6+2\times3=12 \end{align*}$ Of the given answers, $3x-1=8$ is the only one of the given equations which is true when $x=3$ .

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