4. Roko and Marko have equally long steps. They are 1600 steps apart from each other. In one minute, Roko takes 80 steps, and Marko takes 60 steps. Who of the two needs to start earlier and how much earlier should they start to meet exactly halfway while walking towards each other? Express the solution in minutes and seconds.
First method:

For half the distance, 800 steps are required. 1 POINT

It takes Roku $800: 80=10$ minutes to do this. 1 POINT

In 10 minutes, Marko walks $10 \cdot 60=600$ steps. 1 POINT

$\begin{array}{ll}\text { Marko needs to start earlier. } & 1 \text { POINT }\end{array}$

Marko needs to start earlier by the amount of time it takes him to walk 200 steps. 1 POINT

In 1 minute, Marko walks 60 steps, so in 3 minutes, he walks 180 steps. 1 POINT

Since he walks 60 steps in 60 seconds,

he will walk the remaining 20 steps in 20 seconds.

2 POINTS

Therefore, Marko needs to start $180+20=200$ seconds earlier than Roku.

1 POINT

Marko needs to start 3 minutes and 20 seconds earlier than Roku.

1 POINT

TOTAL 10 POINTS