SOLUTION: The destination of your trip is 456 miles away. How much time will you need to make the trip if you drive 75 miles per hour and take 4 rest stops that average 2

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Question 770058:





The destination of your trip is 456 miles away. How much time will you need to make the trip if you drive 75 miles per hour and take 4 rest stops that average 21 minutes each? Round your answer to the nearest tenth.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +t+ = time in hrs for trip
+t+-+4%2A%2821%2F60%29+ = actual time spent driving
+t+-+21%2F15+
+t+-+7%2F5+ hrs
+456+=+75%2A%28t+-+7%2F5%29+
+456+=+75t+-+7%2A15+
+75t+=+456+%2B+105+
+75t+=+561+
+t+=+7.48+
You need 7.5 hrs
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check:
+21%2F15+=+1.4+
+456+=+75%2A%28+t+-+1.4+%29+
+456+=+75t+-+105+
+75%2A7.48+=+456+%2B+105+
+561+=+561+
OK