Madhya Pradesh Police Exam Model Paper 10

Given:
Distance by car driving (x) = 30 km/hr.
Returns to the starting point (y) = 20 km/hr.
Formula used:
Average speed $=\left(2\mathit{x}\mathit{y}\right)/\left(\mathit{x}+\mathit{y}\right)$
Calculation:
$\left(2\times 30\times 20\right)/\left(30+20\right)$ km/hr.
$\Rightarrow \left(2\times 30\times 20\right)/50$ km/hr.
⇒ 24 km/hr.
∴ The average speed is 24 km/hr.