Question 1018390: At 9AM a train traveling 60 miles per hour leaves Los Angeles for San Francisco, a distance of 400 miles. At noon a car traveling at an average speed of 40 miles per hour leaves San Francisco for Los Angeles. At what time will the two vehicles pass each other? Please help! I know I need to draw a graph,but I am having trouble with writing an equation!
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! At 9AM a train traveling 60 miles per hour leaves Los Angeles for San Francisco, a distance of 400 miles. At noon a car traveling at an average speed of 40 miles per hour leaves San Francisco for Los Angeles.
At what time will the two vehicles pass each other?
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LA to SanFran DATA:
rate = 60 mph ; distance = x miles ; time = d/r = x/60 hrs
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SanFran to LA DATA:
rate = 40 mph ; tistance = 400-x ; time = d/r = (400-x)/40 hrs
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Equation:
to SF time = to LA time + 3 hrs
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x/60 = (400-x)/40 + 3 hrs
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40x = 60(400-x) + 3*60*40
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40x = 24000 - 60x + 7200
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100x = 31200
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x = 312 miles (distance of LA to SF car)
time = 312 miles/60 mph = 5.2 hrs
clock time = 9+5.2 = 14.2 = 2:12PM
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Cheers,
Stan H.
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