Final answer:
Joe takes 5.92 hours to cycle to school and 2.96 hours to return home at an average speed of 25 km/h, resulting in a total round trip time of 8.88 hours.
Step-by-step explanation:
To determine how long it takes Joe to go to school and back home with an average speed of 25 km/h, we need to calculate the time for each leg of the trip separately and add them up. First, we calculate the time it takes to travel one way. Since the distance to school is 74 km, the time for one way at an average speed of 25 km/h is time = distance/speed, which is 74 km / 25 km/h = 2.96 hours. Since it takes him twice as long to go to school, it would take 2.96 hours x 2 = 5.92 hours to get to school. The return trip takes 2.96 hours. Therefore, the total time for both trips is 5.92 hours + 2.96 hours = 8.88 hours.