A bus runs at 54 km/h when moving (no stoppage) but averages 45 km/h including stops. On average, how many minutes per hour does the bus stop?

Introduction / Context:
As with trains, the difference between running speed and overall average indicates stoppage time. Compute moving time t per hour, then convert the idle portion to minutes.

Given Data / Assumptions:

• Running speed = 54 km/h.
• Overall average = 45 km/h across 1 clock-hour.

Concept / Approach:
Let moving time = t hours. Then 54t = 45 ⇒ t = 45/54 = 5/6 h = 50 min. Stoppage = 10 min per hour.

Step-by-Step Solution:

Verification / Alternative check:
Distance in 50 minutes at 54 km/h is 45 km; over 60 minutes this averages 45 km/h.

Why Other Options Are Wrong:
4, 6, 8, 12 minutes correspond to wrong t values.

Common Pitfalls:
Arithmetic mean mistakes; not converting fractional hours to minutes properly.

Final Answer:
10 min