Ardi and Lei are both travelling by train.

Ardi’s train travels 70 km in 35 minutes.

Lei’s train travels 585 km.

It leaves at 9:05 and arrives at 13:35.

Work out the difference, in km/h, between the average speed of their trains.

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Answer:

10 kilometer/hour

Step-by-step explanation:

Average speed = Total distance travelled / Total time taken

Ardi:

Total distance travelled = 70 km

Total time taken = 35 minutes = 35/60 hour

Average speed = Total distance travelled / Total time taken

= 70 km ÷ 35/60 hr

= 70 × 60/35

= 4,200/35

= 120 kilometer/hour

Lei:

Total distance travelled = 585 km Total time taken = 9:05 – 13:35 = 4 hours 30 minutes

= 4.5 hours

Average speed = Total distance travelled / Total time taken

= 585 km / 4.5 hours

= 130 kilometer/hour

Difference, in km/h, between the average speed of their trains = Lei’s train – Ardi’s train

= 130 kilometer/hour – 120 kilometer/hour

= 10 kilometer/hour