document.write( "Question 136427: In a race you need to avg. 2 laps at 60 mph. If you go 30 mph in the first lap how fast must you go in the second lap to avg. 60 mph for both laps. \n" ); document.write( "
Algebra.Com's Answer #99938 by ptaylor(2198)\"\" \"About 
You can put this solution on YOUR website!
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( "First of all, lets deal in minutes. Also, in this case, we can assume that 1 lap is equivalent to 1 mi although we do not necessarily need to. 60 mi/hr =1 mi/min; 30 mi/hr=0.5 mi/min\r
\n" ); document.write( "\n" ); document.write( "Average rate equals (total distance) divided by (total time). Total distance in this case is 2 laps and total time has to equal 2 min in order to achieve and average rate of 60 mph or 1 lap/min. On the first lap, we are told, that he averaged 0.5 lap per min or 1 lap in 2 minutes. This means that he used up his alloted time (2 min) already running the first lap. It's therefore impossible to achieve an overall average of 1 lap/min (or 60 mi/hr). \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Let r=speed needed in second lap to have an average of 1 lap/min
\n" ); document.write( "time for first lap=1/0.5 lap/min
\n" ); document.write( "time for second lap=1/r lap/min\r
\n" ); document.write( "\n" ); document.write( "So our eq to solve is:\r
\n" ); document.write( "\n" ); document.write( "Total time=time of first lap + time of 2nd lap or:\r
\n" ); document.write( "\n" ); document.write( "2=1/0.5 + 1/r multiply each term by 0.5r\r
\n" ); document.write( "\n" ); document.write( "r=r+0.5-------------------------------NO SOLUTION !!!!\r
\n" ); document.write( "\n" ); document.write( "Hope this helps---ptaylor\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "
\n" );