Explanation:

- Both the bus and scooter start together from point P and travel to point Q, which is 60 km away.

- The bus is 20% faster than the scooter.

- However, the bus stops for 10 minutes during the journey.

- Both arrive at the same time, showing the bus compensated for its stoppage with a higher speed.

Calculations:

- Let the speed of the scooter be $x$ km/h. Therefore, the bus's speed is $1.2x$ km/h.

- Time taken by the scooter = $\frac{60}{x}$ hours.

- Time taken by the bus = $\frac{60}{1.2x}$ + $\frac{10}{60}$ (convert 10 minutes to hours).

- Both times must be equal: $\frac{60}{x}=\frac{60}{1.2x}+\frac{1}{6}$.

- Solving gives $x=60$ km/h, making the bus's speed $1.2\times 60=72$ km/h.

Correct Answer: Option 4 - 72 km/h