SOLUTION: Could someone please explain to me step by step how to complete this problem? I am able to get to the part where you simplify but am not able to get no farther.
During the first p
Question 526139: Could someone please explain to me step by step how to complete this problem? I am able to get to the part where you simplify but am not able to get no farther.
During the first part of a trip, a canoeist travels 91 miles at a certain speed. The canoeist travels 2 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?
You can put this solution on YOUR website! During the first part of a trip, a canoeist travels 61 miles at a certain speed.
The canoeist travels 2 miles on the second part of the trip at a speed 5 mph slower.
The total time for the trip is 3 hours. What was the speed on each part of the trip?
:
Let s = the speed for the 1st 61 mi
then
(s-5) = the speed for the last 2 mi
:
Write a time equation, time = dist/speed
:
faster time + slower time = 3 hrs + = 3
:
multiply by s(s-5), results:
61(s-5) + 2s = 3s(s-5)
:
61s - 305 + 2s = 3s^2 - 15s
63s - 305 = 3s^2 - 15s
Arrange as a quadratic equation on the right
0 = 3s^2 - 15s - 63s + 305
3s^2 - 78s + 305 = 0
Use the quadratic formula to find s:
In this problem, a=3, b=-78, c=305, x=s
:
:
Two solutions
s =
s = 21.206
and
s =
s = 4.794
:
Obviously the only reasonable solution:
s = 21.206 mph on the first 61 mi
and
16.206 mph on the last two miles
:
:
See if that check out, find the actual time of each
61/21.206 = 2.876 hrs
2/16.206 = .123 hrs
----------------------
total time: 3.0 hrs
