Question

A car covers $40\text{km}$ at a uniform speed of $80\text{km/h}$ and the next $40\text{km}$ at a uniform speed of $100\text{km/h}$. Find the average speed of the car during its entire journey.

• A. $82\text{km/h}$
• B. $85\text{km/h}$
• C. $89\text{km/h}$
• D. $92\text{km/h}$

Answer 1

The correct option is C $89\text{km/h}$

We know that, average speed,

$v=\frac{\text{Total distance}}{\text{Total time}}$

$=\frac{40+40}{40/80+40/100}\approx 89\text{km/h}$