SOLUTION: The distance between two cities is ninety miles, and a woman drives from one city to the other at a rate of forty-five mph. At what rate must she return if the total travel time is
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Question 198981: The distance between two cities is ninety miles, and a woman drives from one city to the other at a rate of forty-five mph. At what rate must she return if the total travel time is three hours and forty minutes? Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! The distance between two cities is ninety miles, and a woman drives from one
city to the other at a rate of forty-five mph.
At what rate must she return if the total travel time is three hours and forty minutes?
:
Let s = speed require to return in 3 hr 40 min
:
Write a time equation: Time = Dist/speed
:
Change time to hrs: 3 & 2/3 hrs = 11/3 hrs
:
To time + return time = 3 hr 40 min + =
Multiply equation by 45s
45s* + 45s* = 45s*
Cancel denominators, results
90s + 45(90) = 15s(11)
90s + 4050 = 165s
4050 = 165s - 90s
4050 = 75s
s =
s = 54 mph required on the return trip
;
:
Check solution
90/45 + 90/54 =
2 + 1.67 = 3.67 hrs ~ 3 hr 40 min
