Question

You travel 80 km in the first 1.00 hour of a trip, 50 km in the next 0.50 hours, and 40 km in the final 0.25 hours. Calculate your average speed for the entire trip?

Answer 1

The average speed is the ratio between the distance covered, and the time elapsed to cover that distance.

The total distance is the sum of the three distances covered:

$d = 80km+50km+40km = 170km$

Similarly, the total time elapsed is

$1h + 0.5h + 0.25h = 1.75h$

So, althought you didn't always travelled with the same speed, you globally covered 170km in 1.75 hours. This leads to an average speed of

$\dfrac{170\text{km}}{1.75\text{h}} \approx 97.14 \dfrac{\text{km}}{\text{h}}$