document.write( "Question 133444: A train averaged 80 km/h for the first half of its trip. How fast must it travel for the second half of the trip in order to average 96 km/h for the whole trip? \n" ); document.write( "

Algebra.Com's Answer #97618 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Distance for whole trip = $\"d\"$
\n" ); document.write( " $\"r\"$ = average rate for 2nd half
\n" ); document.write( " $\"t%5B1%5D\"$ = time for 1st half
\n" ); document.write( " $\"t%5B2%5D\"$ = time for 2nd half
\n" ); document.write( " $\"t\"$ = time for whole trip
\n" ); document.write( " $\"t+=+t%5B1%5D+%2B+t%5B2%5D\"$
\n" ); document.write( " $\"t%5B1%5D+=+%28d%2F2%29%2F80\"$
\n" ); document.write( " $\"t%5B2%5D+=+%28d%2F2%29%2Fr\"$
\n" ); document.write( " $\"t+=+d%2F96\"$
\n" ); document.write( " $\"%28d%2F2%29%2F80+%2B+%28d%2F2%29%2Fr+=+d+%2F+96\"$
\n" ); document.write( " $\"1%2F160+%2B+1%2F%282r%29+=+1%2F96\"$
\n" ); document.write( "multiply both sides by $\"16r\"$
\n" ); document.write( " $\"r%2F10+%2B+8+=+r%2F6\"$
\n" ); document.write( " $\"6r+%2B+480+=+10r\"$
\n" ); document.write( " $\"4r+=+480\"$
\n" ); document.write( " $\"r+=+120\"$ km/hr
\n" ); document.write( "The train must travel 120 km/hr for the 2nd half
\n" ); document.write( "to average 96 km for the whole trip\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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