document.write( "Question 908074: if you drive a car 135 miles and have a mean of a certain speed. if the mean speed had been 4 mph more, you could have traveled 144 miles in the same time. what was the mean speed? \n" ); document.write( "

Algebra.Com's Answer #550792 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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if you drive a car 135 miles and have a mean of a certain speed.
\n" ); document.write( " if the mean speed had been 4 mph more, you could have traveled 144 miles in the same time.
\n" ); document.write( " what was the mean speed?
\n" ); document.write( ":
\n" ); document.write( "let s = the mean speed
\n" ); document.write( "then
\n" ); document.write( "(s+4) = the faster speed
\n" ); document.write( ":
\n" ); document.write( "Write a time equation, time = dist/speed
\n" ); document.write( "actual time = faster speed time
\n" ); document.write( " $\"135%2Fs\"$ = $\"144%2F%28%28s%2B4%29%29\"$
\n" ); document.write( "Cross multiply
\n" ); document.write( "144s = 135(s+4)
\n" ); document.write( "144s = 135s + 540
\n" ); document.write( "144s - 135s = 540
\n" ); document.write( "s = 540/9
\n" ); document.write( "s = 60 mph is the mean speed
\n" ); document.write( ":
\n" ); document.write( ";
\n" ); document.write( "you can confirm this, find the actual time at each speed, should be the same
\n" ); document.write( "135/60 = 2.25 hr
\n" ); document.write( "144/64 = 2.25 hr \n" ); document.write( "

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