The Delhi metro train covers a distance of 42 km in 80 minutes. What is…

Average speed for a single continuous journey is the total distance covered divided by the total time taken, with both quantities expressed in consistent units. Here the time is given in minutes, so it must be converted to hours (or the distance converted to a consistent per-minute rate) before dividing.

Applying this to the given values:

1. Total distance = 42 km = 42000 m; total time taken = 80 minutes.

2. Speed in metres per minute = distance ÷ time = 42000 ÷ 80 = 525 m/min.

3. Convert m/min to km/h: multiply by 60 (minutes to hours) and divide by 1000 (metres to kilometres): 525 × 60 ÷ 1000 = 31.5 km/h.

Cross-check using hours directly:

80 minutes = 4/3 hour, so average speed = 42 ÷ (4/3) = 42 × 3/4 = 31.5 km/h, which matches the value obtained above.

Hence, the average speed of the train is 31.5 km/h.