document.write( "Question 37145: HELP!!! I have worked this problem and can't get it.\r
\n" ); document.write( "\n" ); document.write( "Problem:\r
\n" ); document.write( "\n" ); document.write( "Jim can run 5 miles per hour on level ground on a still day. One windy day, he runs 10 miles with the wind, and in the same amount of time runs 4 miles against the wind. What is the rate of the wind? \n" ); document.write( "

Algebra.Com's Answer #22827 by fractalier(6550) $\"\"$ $\"About$

You can put this solution on YOUR website!
Okay. The governing equation for this kind of problem is RT = D. Rate times time equals distance. His rate (with no wind) is given as 5 mph. Then we set up two equations, one with the wind and one against:\r
\n" ); document.write( "\n" ); document.write( "(R + W)T = D
\n" ); document.write( "(R - W)T = D\r
\n" ); document.write( "\n" ); document.write( "now substitute in what you know\r
\n" ); document.write( "\n" ); document.write( "(5 + W)T = 10
\n" ); document.write( "(5 - W)T = 4\r
\n" ); document.write( "\n" ); document.write( "If we solve the second one for T \r
\n" ); document.write( "\n" ); document.write( "T = 4 / (5 - W)\r
\n" ); document.write( "\n" ); document.write( "and then plug it in to the first equation, we get\r
\n" ); document.write( "\n" ); document.write( "(5 + W)( 4 / (5 - W)) = 10\r
\n" ); document.write( "\n" ); document.write( "Solving this we get W = 15/7 or about 2.143 mph, the wind speed. \n" ); document.write( "

\n" );