Question

A person is walking briskly in a straight line. The figure shows a graph of the person’s position x as a function of time t. What is the person’s average velocity between t = 6 s and t = 10 s?

Answer 1

The average velocity over the interval $6\le t\le 10$ is

$\dfrac{x(10)-x(6)}{10\,\mathrm s-6\,\mathrm s}=\dfrac{6\,\mathrm m-2.67\,\mathrm m}{4\,\mathrm s}=0.8325\,\dfrac{\mathrm m}{\mathrm s}$

where $x(t)$ is the person's position at time $t$. I've taken the liberty of estimating $x(6)\approx2.67\,\mathrm m$. The closest choice among the answers is $0.8\,\dfrac{\mathrm m}{\mathrm s}$.