SOLUTION: Some bank robbers leave town, speeding at 100 mph. 15 minutes later, the police give chase, traveling at 110 mph. How long (in hours) will it take the police to overtake the robber

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Question 756904: Some bank robbers leave town, speeding at 100 mph. 15 minutes later, the police give chase, traveling at 110 mph. How long (in hours) will it take the police to overtake the robbers?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Convert +15+ min to +.25+ hrs
The robbers have a head start of
+d%5B1%5D+=+100%2A%28.25+%29+
+d%5B1%5D+=+25+ mi
----------------
Start a stopwatch when the police leave.
Let +t+ = time on stopwatch when police catch robbers
Let +d+ = the distance the police travel until they catch robbers
----------------
Robbers equation:
++d+-+25+=+100t+
Police equation:
+d+=+110t+
------------
By substitution:
+110t+-+25+=+100t+
+10t+=+25+
+t+=+2.5+
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It takes the police 2 hrs and 30 min to catch robbers
check:
+d+=+110t+
+d+=+110%2A2.5+
+d+=+275+
and
++d+-+25+=+100%2A2.5+
+d+=+25+%2B+250+
+d+=+275+
OK