Problema Solution
During the first part of a trip, a canoeist travels 28
miles at a certain speed. The canoeist travels 9
miles on the second part of the trip at a speed 5 mph slower. The total time for the trip is 3 hrs. What was the speed on each part of the trip?
Answer provided by our tutors
Let
t = the time for the 1st trip
3 - t = time for the 2nd trip
s = the speed for the 1st trip
s - 5 = the speed for the 2nd trip, s-5 >=0, s>=5
1st part of the trip:
28 = s*t
2nd part of the trip:
9 = ( s - 5 )*( 3 - t )
s*t = 28 follows t = 28/s
Plug t = 28/s into ( s - 5 )*( 3 - t ) = 9:
(s - 5)*(3 - 28/s) = 9
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click here to see the equation solved for s
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s = 14 mph
s - 5 = 14 - 5 = 9 mph
The speed od the first part of the trip was 14 mph, while on the second part of the trip, 9 mph.