document.write( "Question 182939: Please help me: Allen drives to a friends house in the next state at 50 mph he returns at a more congested time and only averages 30 mph. What is the average speed in mph for the entire trip? \n" ); document.write( "
Algebra.Com's Answer #137404 by ptaylor(2198)\"\" \"About 
You can put this solution on YOUR website!

\n" ); document.write( "Distance(d) equals Rate(r) times Time(t) or d=rt; r=d/t and t=d/r\r
\n" ); document.write( "\n" ); document.write( "Average Speed =(Total Distance)/(Total Time)
\n" ); document.write( "Let t1=time going
\n" ); document.write( "And t2=time returning
\n" ); document.write( "So t1+t2=Total Time
\n" ); document.write( "Distance going=50* t1
\n" ); document.write( "Distance returning=30*t2
\n" ); document.write( "Total Distance=50t1+30t2
\n" ); document.write( "Average Speed=(50t1+30t2)/(t1+t2)--------------------eq1
\n" ); document.write( "but
\n" ); document.write( "Distance going=Distance returning, so:
\n" ); document.write( "50t1=30t2
\n" ); document.write( "t1=(3/5)t2
\n" ); document.write( "Substitute into eq1
\n" ); document.write( "Average Speed=(50*(3/5)t2+30t2)/((3/5)t2+t2)
\n" ); document.write( "Average Speed=60t2/(8/5)t2 the t2's cancel, so we have
\n" ); document.write( "Average Speed=60/(8/5)=60*5/8=300/8=37.5 mph-------------------Ans\r
\n" ); document.write( "\n" ); document.write( "Hope this helps---ptaylor
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