SOLUTION: During the first part of a trip, a canoeist travels 90 miles at a certain speed. The canoeist travels 12 miles on the second part of the trip at a speed 5mph slower. The total time
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Question 470745: During the first part of a trip, a canoeist travels 90 miles at a certain speed. The canoeist travels 12 miles on the second part of the trip at a speed 5mph slower. The total time for the trip is 5 hrs. What was the speed on each part of the trip?
1.Speed of 1st part of the trip?
2.Speed of 2nd part of the trip?
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
first part x mph
second part -5 mph
first part 90 miles
second part 12 miles
speed in first part x mph
speed second part x -5 mph
Total rowing time 5 hours
Time first part 90 / x
Time second part 12 / ( x -5 )
Time first part + time second part = 5 hours
90/x+12/(x-5)= 5
LCD =(x)*(x-5)
multiply the equation by the LCD
we get
90*(x-5)+12x = 5
90x-450+ 12x=5x^2-25x
127x-450 =5x^2
5X^2-127 x+450=0
5X^2-127 x+450 =0
/5
x^2-25.4 x+90=0
Find the roots of the equation by quadratic formula a= 1 b= -25.4 c= 90
b^2-4ac= 645.16-( -360)
b^2-4ac= 285.16
= 16.89
x1=( 25.4 + 16.89 )/ 2
x1= 21.14 ====> 21 1/7
x2=( 25.4 -16.89 ) / 2
x2= 4.26 ===> 4 1/4 (Ignore this value)
x = 21.14 mph LCD =speed
first part 21.94 mph
seond part 21.14-5=16.14 mph
m.ananth@hotmail.ca
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