Chapter 2 - Kinematics: Description of Motion - Learning Path Questions and Exercises - Exercises - Page 60: 3

It takes the sprinter $9.85\,\mathrm{s}$ to run $100\,\mathrm{m}$.

Conversion - $100\,\mathrm{yd}=91.41\,\mathrm{m}$ Speed of the sprinter,\begin{align*} s&=\frac{d}{t}=\frac{91.41}{9}\\&=10.16\,\mathrm{m/s} \end{align*}Now, time taken to run $100\,\mathrm{m}$, \begin{align*} t&=\frac{d}{s}=\frac{100}{10.16}\\&=9.85\,\mathrm{s} \end{align*}