Answer:
120 miles/hour
Step-by-step explanation:
The average speed is the ratio of total distance covered by an object or a body to the total time taken to cover the distance.
Mathematically,
Average speed = total distance covered/total time taken
In the case of Connie:
total distance = 180 + 180 = 360 miles
In order to calculate the time for each trip
speed = distance/time
time = distance/speed
From Phoenix to flagstaff:
time = 180/180 = 1 hour
From flagstaff back to Phoenix:
time = 180/90 = 2 hours
total time taken = 1 + 2 = 3 hours
Average speed = 360/3 = 120 miles/hour
Hence, the average speed is 120 miles per hour.