Problema Solution
A truck enters a highway driving 60 mph. A car enters the highway at the same place 9 minutes later and drives 71 mph in the same direction. From the time the car enters the highway, how long will it take the car to pass the truck?
Answer provided by our tutors
let
t = the time that the car needs to pass the truck
t + 9/60 = the time that the truck is driving till the car passes by
v1 = 60 mph the speed of the truck
v2 = 71 mph the speed of the car
since distance = speed*time
v1*(t + 9/60) = v2*t
60(t + 9/60) = 71*t
by solving the equation we find
t = 9/11 hours
t = 9*60/11 min
t = 49.1 min
it takes 49.1 min for the car to pass the truck.