document.write( "Question 890470: A motorist travels A to B at a speed at 40 km/h and returns at speed of 60 km/h. his average speed will be: \n" ); document.write( "

Algebra.Com's Answer #539028 by Alan3354(69443) $\"\"$ $\"About$

You can put this solution on YOUR website!
A motorist travels A to B at a speed at 40 km/h and returns at speed of 60 km/h. his average speed will be between 40 & 60.
\n" ); document.write( "--------------
\n" ); document.write( "Use d = r*t
\n" ); document.write( "t = d/r
\n" ); document.write( "d = distance one way.
\n" ); document.write( "Total time = d/40 + d/60
\n" ); document.write( "Round trip avg = $\"2d%2Ft+=+2d%2F%28d%2F40+%2B+d%2F60%29\"$
\n" ); document.write( "= $\"2%2F%281%2F40+%2B+1%2F60%29\"$
\n" ); document.write( "= 2*40*60/(40+60)
\n" ); document.write( "= 48 km/hr
\n" ); document.write( "----------------
\n" ); document.write( "Notice it's similar to parallel resistors and parallel flows.
\n" ); document.write( "Avg = 2*r1*r2/(r1 + r2)
\n" ); document.write( "==============
\n" ); document.write( "Also notice the distance is not a factor. \n" ); document.write( "

\n" );