SOLUTION: After robbing a bank in Dodge City, a robber gallops off at 12 mi/h. 10 minutes later, the marshall leaves to pursue the robber at 16 mi/h. How long (in hours) does it take the mar

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: After robbing a bank in Dodge City, a robber gallops off at 12 mi/h. 10 minutes later, the marshall leaves to pursue the robber at 16 mi/h. How long (in hours) does it take the mar      Log On

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Question 763744: After robbing a bank in Dodge City, a robber gallops off at 12 mi/h. 10 minutes later, the marshall leaves to pursue the robber at 16 mi/h. How long (in hours) does it take the marshall to catch up to the robber?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Convert +10+ min to hours
+10%2F60+ hrs
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What is the robbers head start in miles?
+d%5B1%5D+=+12%2A%28+10%2F60+%29+
+d%5B1%5D+=+2+ mi
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Start a stopwatch when the marshall leaves
Let +t+ = time on stopwatch when he catches robber
Let +d+ = distance in miles that Marshall has to go
until he catches robber
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Robber's equation:
(1) +d+-+2+=+12t+
Marshall's equation:
(2) +d+=+16t+
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Substitute (2) into (1)
(1) +16t+-+2+=+12t+
(1) +4t+=+2+
(1) +t+=+1%2F2+
the marshall catches robber in a half-hour
check:
(2) +d+=+16t+
(2) +d+=+16%2A.5+
(2) +d+=+8+
and
(1) +d+-+2+=+12%2A.5+
(1) +d+=+2+%2B+6+
(1) +d+=+8+
OK