Calculating Speed of a Moving Train

Explanation:

Acceleration: The train accelerates at 60 km/h/s for 0.75 hours. To find the increase in speed due to acceleration, we multiply the acceleration rate by the time: 60 km/h x 0.75 h = 45 km/h.

Adding up the Speeds: Next, we need to add the acceleration to the speed the train was already moving at. The train was initially moving at 4.0 km/h. By adding the acceleration of 45 km/h to the initial speed, we get: 45 km/h + 4.0 km/h = 49 km/h.

Therefore, the speed of the train by the end of the 0.75 hours is 49 km/h.