Problema Solution
Walter travels up on a hill at 40 mph and back down at 70 mph. What is the average speed for the entire trip?
Answer provided by our tutors
the average speed = total distance/total time
let
d = the distance up hill = the distance downhill
v1 = 40 mph the speed uphill
t1 = the time of the travel uphill
v2 = 70 mph the speed downhill
t2 = the time of the travel downhill
since speed = distance/time => time = distance/speed
t1 = d/v1
t1 = d/40
t2 = d/v2
t2 = d/70
the total time of the travel t = t1 + t2
t = d/40 + d/70
t = d(1/40 + 1/70)
the average speed
v = 2d/t
v = 2d/(d(1/40 + 1/70))
v = 2/(1/40 + 1/70)
v = 50.91 mph
click here to see the step by step calculation
the average speed for the entire trip is 50.91 mph.