SOLUTION: A train goes from New Orleans to Boston at a speed of 40 mph. On the return journey it moves at a speed of 80 mph. If the return journey takes an hour less than the outward journey

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Question 728479: A train goes from New Orleans to Boston at a speed of 40 mph. On the return journey it moves at a speed of 80 mph. If the return journey takes an hour less than the outward journey, what is the average speed overall of the train?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Average speed = ( total distance ) / ( total time )
1st trip:
+d+=+40t+
2nd trip:
+d+=+80%2A%28+t+-+1+%29+
-----------------
By sustitution:
+40t+=+80%2A%28+t+-+1+%29+
+40t+=+80t+-+80+
+40t+=+80+
+t+=+2+
----------
+d+=+40t+
+d+=+40%2A2+
+d+=+80+
The distance traveled is +2d+
+2d+=+160+
The total time is +t+%2B+t+-+1+=+2%2A2+-+1+
+2%2A2+-+1+=+3+
----------------
( total distance ) / ( total time ) = +160%2F3+
+160%2F3+=+53.333+
The average speed is 53.333 mi/hr