Question

Dina and Masha start cycling on a 20 km bike path at the same time. When Dina reaches the end of the path, Masha still has 4 km of the path left to cycle. If Dina's cycling speed is 10 km/h, how much time longer will Masha need to complete the path?

Answer 1

30 minutes

Explanation:

Answer 2

0.5 hour

Explanation:

Given

Speed of Dina = 10 km/h

Distance = 20 km

So the time Dina taken to complete the track is:

`Speed=(distance)/(time)\\10=(20)/(time)\\time=(20)/(10)\\ time=2\ hours`

The time taken by Dina is 2 hours. As masha started with dina but she was 4 km of the path left to cycle,

her distance covered in 2 hours was:

`Distance\ covered\ by\ Masha\ in\ 2\ hours=20-4\\=16 km`

So we know the time and distance:

Now,

`Speed\ of\ Masha=(distance)/(time)\\ =(16)/(2)\\ =8\ kilometer\ per\ hour`

We have to calculate the time that will be needed by MAsha to complete the track:

As we know the speed and remaining distance

`Speed=(distance)/(time)\\8=(4)/(time)\\ time=(4)/(8)\\time=0.5\ hours`

Masha needs 0.5 hour to complete the track ..