Question 493783
A truck enters a highway driving 60 mph. A car enters the highway at the same place 9 minutes later and drives 69 mph in the same direction. From the time the car enters the highway, how long will it take the car to pass the truck?
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Apply the distance formula of d=rt
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Since speed is given in terms of "hours" we must convert 9 minutes to hours:
9 minutes = 9/60 hours = 3/20 hours
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Let x = time (hours) it takes car to pass the truck
then
60(x + 3/20) = 69x
multiplying both sides by 20:
60(20x + 3) = 1380x
1200x + 180 = 1380x
180 = 180x
1 hour = x