Question

A joirney takes 1 hour and 30 minutes. Half the distance is travelled at an average apeed of 90km/h, while the ramaining distance is covered at an average speed of 100km/h. how long is the journey to the nearrst killometre?

Answer 1

According to, the average speed formula is:

Average Speed = Total Distance / Total Time

Let x be the distance travelled at 90 km/h and y be the distance travelled at 100 km/h. Then we have:

x + y = Total Distance

x / 90 + y / 100 = 1.5 (Total Time in hours)

Solving for x and y, we get:

x = 60 km

y = 75 km

Therefore, the total distance is x + y = 135 km.

The average speed is then:

Average Speed = Total Distance / Total Time

= 135 / 1.5

= 90 km/h