Answer:
Option B. 15miles.
Step-by-step explanation:
From the question given, in the 4th hour simply means between 3rd and 4th hour.
Now, let us determine the position of the object at the 3rd and 4th hour. This is illustrated below:
At the 3rd hour:
Position (P3) = 60miles
At the 4th hour:
Position (P4) = 75miles
Finally, we shall determine the change in the position of the object as follow:
Change in the position = P4 – P3
Change in the position = 75 – 60
Change in the position = 15 miles
Therefore, the change in the position of the object in the 4th hour is 15miles.