Alex rode his bike to school at a speed of 12 mph. He then walked home at a speed of 5 mph. What was Alex's average speed for his trip to school and back?
Say the distance was 1 mile from school to home
D = rt
To school
1 = 12t
t = 1/12
From school:
1 = 5t
t = 1/5
1/2(1/12 + 1/5)
1/24 + 1/10 = 17/120
120 = Average speed * 17
Average speed = 120/17 = 7.06 mph
Say the distance was 1 mile from school to home
D = rt
To school
1 = 12t
t = 1/12
From school:
1 = 5t
t = 1/5
1/2(1/12 + 1/5)
1/24 + 1/10 = 17/120
120 = Average speed * 17
Average speed = 120/17 = 7.06 mph