Chris A. answered • 01/20/20
Recent Mech Engineering Grad and CLRA certified Tutor
Solving this problem is completely dependent on keeping your units straight.
First lets figure out the total distance traveled. We can find a distance by multiplying a velocity by a time. In order to do this we have to convert the time to hours so the units match with the velocity in Km/hr.
30.1 [min] * 1/60 [hr/min] = .5017 [hr]
.50174 [hr] * 52.7 [km/hr] = 26.437 [km]
54.9 [min] *1/60 [hr/min] = .915 [hr]
.915 [hr] * 93.9 [km/hr] = 85.9185 [km]
total distance = 26.437 [km] + 85.9185 [km] = 112.3555 [km]
total time = .5017 [hr] + .915 [hr] = 1.4167 [hr]
average velocity = total distance/ total time = 112.3555 [km] / 1.4167 [hr] = 79.307 [km/hr]
This is the simplest way to solve this problem, however, your teacher may show you a method called "weighted average" to solve problems like this. Just know that both methods are essentially the same will yield the same answer. If you have any questions, or want to see alternate ways to solve this, please reach out!
