Question

A car travelled the first one-third of the distance $d$ at a speed of $\frac{55}{9}{\text{kmh}}^{-1}$, the second one-third of the distance at a speed of $\frac{110}{9}{\text{kmh}}^{-1}$ and the last one-third of the distance at a speed of $\frac{165}{9}{\text{kmh}}^{-1}$. Determine the average speed of the car(in $km/h$)

Answer 1

$\text{Average speed}=\frac{\text{Total distance travelled}}{\text{Total time taken}}$

$\Rightarrow \text{Average speed}=\frac{d/3+d/3+d/3}{\frac{d/3}{55/9}+\frac{d/3}{110/9}+\frac{d/3}{165/9}}$
= 10 km/h