Final answer:
To find the average speed, divide the total distance traveled by the total time taken. In this case, the average speed needed to make the trip in the desired time is 40 mph.
Step-by-step explanation:
To find the average speed, we divide the total distance traveled by the total time it took to travel that distance. In this case, Ella's family plans to drive 120 miles in 3 hours. So, the average speed would be:
Average Speed = Total Distance / Total Time
Average Speed = 120 miles / 3 hours
Average Speed = 40 miles per hour
Therefore, the average speed needed to make the trip in the desired time is 40 mph