After converting minutes to seconds, use the formula $\text{distance} = \text{speed} \times \text{time}$ to find how many meters the train travels in that time.

Once you have the distance in meters, remember that $1$ kilometer equals $1000$ meters. How do you change meters into kilometers using this fact?

In a Desmos expression line, type 150*4*60/1000. This expression multiplies the speed by the time in seconds and then divides by 1000 to convert meters to kilometers.

Look at the value Desmos displays to the right of the expression. That value is the number of kilometers the train travels in 4 minutes at 150 meters per second.

The speed is given in meters per second, so the time must be in seconds.

Convert $4$ minutes to seconds:

Distance traveled at constant speed is

Here, speed $=150$ meters per second and time $=240$ seconds, so

The train travels $36{,}000$ meters in $4$ minutes.

We are asked for the distance in kilometers, and we know that

So to convert $36{,}000$ meters to kilometers, divide by $1000$:

Now perform the division:

So, the train will travel 36 kilometers in $4$ minutes.