SOLUTION: Chelsea went on a 102 mile trip to a soccer game. On the way back, due to road construction she had to drive 17 miles per hour slower. This made the trip 1 hour longer. How fast di
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Question 1150378: Chelsea went on a 102 mile trip to a soccer game. On the way back, due to road construction she had to drive 17 miles per hour slower. This made the trip 1 hour longer. How fast did she drive to the soccer game? Found 2 solutions by nijneweed, ikleyn:Answer by nijneweed(6) (Show Source):
Let "x" be the rate on the way to the game.
Then you have this "time" equation
- = 1
saying that the difference in times going and back is 1 hour.
Multiply both sides by x*(x-17).
102x - 102*(x-17) = x*(x-17
102*17 = x^2 - 17x
x^2 - 17x - 1734 = 0
= = .
Only positive root makes sense x = = 51.
ANSWER. The rate on the way to the soccer game was 51 mph.
CHECK. + = - = 3 - 2 = 1 hour. ! Correct !
Solved.
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Using "time" equation is the STANDARD method of solving such problems.
It is simple, logical, straightforward, economic and robust (work in standard way for any input data).
Going in this way, you will never make a mistake - the logic of the method
prevents you of making mistakes.
From this lesson, learn on how to write, how to use and how to solve a "time" equation.
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