Question

A car travels $100km$ at a speed of $60km/h$ and returns with a speed of $40km/h$. Calculate speed for the hole journey.

• A. 48 m/s
• B. 480 km/hr
• C. 48 km/hr
• D. 48 m/hr

Answer 1

The correct option is C 48 km/hr

Using speed $=\frac{Distance}{Time}$

$\Rightarrow Time=\frac{distance}{speed}$

We have total time $=\frac{100}{60}+\frac{100}{40}=\frac{25}{6}Hr$

Now, Average speed $=\frac{Distanc{e}_{\left(tot\right)}}{Tim{e}_{\left(tot\right)}}=\frac{200}{\frac{25}{6}}$

$\Rightarrow$ Average spped $=\frac{1200}{25}=48km/h$