Answer:
Option A. 40 mi/h
Step-by-step explanation:
To obtain the average speed of the vehicle, we'll begin by calculating the distance travelled by the vehicle in each case. This is illustrated below:
Case 1:
Speed = 30 mi/h
Time = 2 h
Distance =...?
Speed = Distance /Time
30 = Distance /2
Cross multiply
Distance = 30 × 2
Distance = 60 mi
Case 2:
Speed = 60 mi/h
Time = 1 h
Distance =...?
Speed = Distance /Time
60 = Distance /1
Cross multiply
Distance = 60 × 1
Distance = 60 mi
Finally, we shall determine the average speed of the vehicle as follow:
Total distance travelled = 60 + 60
Total distance travelled = 120 mi
Total time = 2 + 1
Total time = 3 h
Average speed =..?
Average speed = Total Distance travelled /Total time
Average speed = 120/3
Average speed = 40 mi/h
Therefore, the average speed of the vehicle is 40 mi/h