Question

Irina walks 10km at 4km/h and then a further 8km at 5km/h.
Calculate Irina's average speed for the whole journey.

Answer 1

Answer:

4.4 km/hour

Step-by-step explanation:

In order to calculate the average speed, we need to find the total distance Irina walked and the total time taken to walk this distance.

For the first given, Irina walks 10 km at 4 km/h.

$velocity=distance/time\\time=distance/velocity\\time=10/4=2.5\:hours$

For the second given, Irina walks 8 km at 5 km/h.

$velocity=distance/time\\time=distance/velocity\\time=8/5=1.6\:hours$

Therefore, total time is 2.5+1.6= 4.1 hours.

Total distance is 10 km + 8 km = 18 km

Therefore the average speed is 18 km/4.1 hours = 4.4 km/hour