Answer:
Average speed = 5.264 km/hr
Explanation:
Distance to highschool = 3.29 km
Average speed = Distance covered ÷ time taken
Distance covered = distance to highschool and back = 3.29 + 3.29 = 6.58 km
time taken = 3:30 pm to 5:15 pm = 5:15 - 3:30 = 1 hr 15 mins
15 minutes = 15/60 hours = 0.25 hours
∴ time taken in hours = 1 + 0.25 = 1.25 hours
∴ Average speed = 6.58 ÷ 1.25 = 5.264 km/hr