document.write( "Question 1078220: A car drove from town A to town B at an average of 60 mph. On the return trip from town B to town A the car took exactly the same route. It was foggy and the car only averaged 40 mph on the return trip. What is the average speed over the entire trip? \n" ); document.write( "

Algebra.Com's Answer #692708 by ikleyn(52788) $\"\"$ $\"About$

You can put this solution on YOUR website!
.
\n" ); document.write( "

\r\n" );
document.write( "Let D be the distance between the cities.\r\n" );
document.write( "\r\n" );
document.write( "Then the time for the trip from A to B is  hours.\r\n" );
document.write( "\r\n" );
document.write( "     The time for the trip from B to A is  hours.\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "The total time for the round trip is  =  =  hours.\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "The length of the round trip is 2D.\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Hence, the average speed is  =  = 48 mph.\r\n" );
document.write( "

\r
\n" ); document.write( "\n" ); document.write( "Solved.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "For the solution of similar problem with detailed explanations see the lesson\r
\n" ); document.write( "\n" ); document.write( " - Calculating an average speed: a train going from A to B and back \r
\n" ); document.write( "\n" ); document.write( "in this site.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

\n" );