2012 CEMC Gauss (Grade 7) Problems/Problem 10

Problem

Consider the given graph.

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(graph with a constant speed of 20 meters per second)

The number of seconds required for a vehicle to travel a total distance of 100 m is

$\text{ (A) }\ 2.5 \qquad\text{ (B) }\ 20 \qquad\text{ (C) }\ 8 \qquad\text{ (D) }\ 10 \qquad\text{ (E) }\ 5$

Through the graph, we can notice that the speed is constant.

This means that we have $st = d$ , where $s$ represents the speed, $t$ represents the time, and $d$ represents the distance.

From the graph and problem, we know that $s = 20 \frac{m}{s}$ , and $d = 100$ m, giving:

$20t = 100$

Solving for t, we get:

$t = 5$ s

Thus, the answer is $\boxed {\textbf { (E) } 5}$ .