Practice!

Sample Problem

Tyler travelled from Town F to Town G. For the first 2.5 hours, he travelled at a constant speed of 60 km/h. For the next 1.5 hours, he travelled at a constant speed of 80 km/h. What was the average speed for the whole journey?

  km/h

Solution

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According to the formula of Average Speed = Total Distance ÷ Total Time, we know that Total Distance and Total Time must be known first if we want to figured out Average Speed.

Distance for the first 2.5 hours: 2.5 × 60 = 150 km

Distance for the next 1.5 hours: 1.5 × 80 = 120 km

Then, total distance: 150 + 120 = 270 km

Total time: 2.5 + 1.5 = 4 h

Thus, average speed: 270 ÷ 4 = 67.5 km/h