SOLUTION: A person travels by car from one city to another with different constant speeds between the cities. She drives 30 min at 80 km/hr, 12 min at 100 km/hr and 45 min at 40 km/hr. Deter

Question 522570: A person travels by car from one city to another with different constant speeds between the cities. She drives 30 min at 80 km/hr, 12 min at 100 km/hr and 45 min at 40 km/hr. Determine the average speed for the trip and determine the distance between the initial and final cities along the trip.
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
A person travels by car from one city to another with different constant speeds between the cities. She drives 30 min at 80 km/hr, 12 min at 100 km/hr and 45 min at 40 km/hr.
Determine the average speed for the trip and determine the distance between the initial and final cities along the trip.
:
Change minutes to hrs, divide by 60:
30 min = .50 hrs
45 min = .75 hrs
12 min = .20 hrs
----------------
total + 1.45 hrs, total travel time
:
let a = average speed for the trip
:
Write a dist equation, dist = speed * time
:
80(.5) + 100(.20) + 40(.75) = 1.45a
40 + 20 + 30 = 1.45a
90 = 1.45a
a =
a = 62.069 km/h, for the entire trip
and
90 km is the total distance
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