SOLUTION: A small airplane flies 945 miles with an average speed of 270 miles per hour.1.75 hours after the plane leaves, a Boeing 747 leaves from the same point. Both planes arrive at the s

Algebra ->  Test -> SOLUTION: A small airplane flies 945 miles with an average speed of 270 miles per hour.1.75 hours after the plane leaves, a Boeing 747 leaves from the same point. Both planes arrive at the s      Log On


   

Question 1055077: A small airplane flies 945 miles with an average speed of 270 miles per hour.1.75 hours after the plane leaves, a Boeing 747 leaves from the same point. Both planes arrive at the same time; what was the average speed of the 747?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
What is the head start of the small plane in miles?
+d%5B1%5D+=+270%2A1.75+
+d%5B1%5D+=+472.5+ mi
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Start a stopwatch when the 747 leaves. Let +t+ =
the time in hrs on the stopwatch when both planes
arrive at the destination.
Let +s+ = the average speed of the 747 in mi/hr
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Equation for the small plane:
(1) +945+-+472.5+=+270t+
Equation for the 747:
(2) +945+=+s%2At+
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(1) +270t+=+472.5+
(1) +t+=+1.75+
Plug this value into (2)
(2) +945+=+s%2A1.75+
(2) +s+=+540+
The average speed of the 747 was 540 mi/hr