SOLUTION: 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 Sa

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Question 1018383: 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?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
What is the headstart for the train in miles?
9 AM to 12 Noon = +3+ hrs
+d%5B1%5D+=+60%2A3+
+d%5B1%5D+=+180+ mi
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Start a stop watch when the car leaves SF
Let +t+ = time in hrs on stop watch when the
2 vehicles pass eachother
Let +d+ = distance in miles the car travels in time +t+
+400+-+d+-+180+ = distance in miles the train travels in
time +t+ on the stop watch
--------------------------
Equation for the train:
(1) +400+-+d+-+180+=+60%2At+
Equation for the car:
(2) +d+=+40t+
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Substitute (2) into (1)
(1) +400+-+40t+-+180+=+60t+
(1) +220+-+40t+=+60t+
(1) +100t+=+220+
(1) +t+=+2.2+
Convert +.2+ hrs to minutes:
+.2%2A60+=+12+
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The 2 vehicles will pass eachother 2 hrs and 12 min
after 12 Noon, which is:
2:12 PM
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check answer:
(2) +d+=+40t+
(2) +d+=+40%2A2.2+
(2) +d+=+88+ mi
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(1) +400+-+d+-+180+=+60%2At+
(1) +400+-+d+-+180+=+60%2A2.2+
(1) +220+-+d+=+132+
(1) +d+=+88+ mi
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OK