SOLUTION: A biker decided to cover the distance of 120 km at a certain speed. However, he actually went 6 km/h slower so he arrived at his destination 1 hour later than he wanted to. What wa
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Question 1019566: A biker decided to cover the distance of 120 km at a certain speed. However, he actually went 6 km/h slower so he arrived at his destination 1 hour later than he wanted to. What was the actual speed of the biker? What is the equation? Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! A biker decided to cover the distance of 120 km at a certain speed.
However, he actually went 6 km/h slower so he arrived at his destination 1 hour later than he wanted to.
What was the actual speed of the biker?
:
let s = actual speed of the biker
He went 6 km/hr slower, therefore
(s+6) = speed he intended to travel
:
Write a time equation time = dist/speed
:
Actual time - intended time = 1 hrs - = 1
multiply equation by s(s+6)
s(s+6)* - s(s+6) = 1s(s+6)
cancel the denominators
120(s+6) - 120s = s^2 + 6s
120s + 720 - 120s = s^2 + 6s
Form a quadratic equation on the right
0 = s^2 + 6s - 720
You can use the quadratic formula; a=1; b=6; c=-720, but this will factor to
(s+30)(s-24) = 0
the positive solution;
s = 24 km/hr actual speed
:
:
Confirm this solution; find the actual time at each speed
120/24 = 5 hrs
120/30 = 4 hrs
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differs: 1 hr
