Question

An athlete runs 100m in 12s. What is his speed in km/hr?

Answer 1

$$S=100m=\frac{100}{1000}=0.1km$$ $$t=12s=\frac{12}{3600} h$$

$$v=\frac{S}{t}=\frac{0.1\times3600}{12}=30 \frac{km}{h}$$