Algebra.Com's Answer #814137 by ikleyn(52787)![\"\"](\"/images/stars/stars-13.gif\")  
You can put this solution on YOUR website!
.
\n" );
document.write( "A certain journey took 40min to complete. If half the distance was travelled at an average speed of 100km per hour
\n" );
document.write( "and the other half at an average speed of 60km per hour, what was the length of the journey.
\n" );
document.write( "Thanks
\n" );
document.write( "Textbook says its 24km.
\n" );
document.write( "~~~~~~~~~~~~~~~\r
\n" );
document.write( "
\n" );
document.write( "\n" );
document.write( "\r\n" );
document.write( "Let d be the length of the journey, in kilometers (the value under the problem's question).\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Then half of the distance is  kilometers.\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "The travel time for the first half of the distance was  hours.\r\n" );
document.write( "\r\n" );
document.write( "The travel time for the second half of the distance was  hours.\r\n" );
document.write( "\r\n" );
document.write( "The total time is 40 minutes, or  of an hour (GIVEN).\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "It gives the \"time\" equation\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( " + = of an hour.\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "To solve the equation, multiply both sides by 600. You will get\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( " 3d + 5d = 2*200\r\n" );
document.write( "\r\n" );
document.write( " 8d = 400\r\n" );
document.write( "\r\n" );
document.write( " d = 400/8 = 50 kilometers. ANSWER\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "CHECK. 1-st half of the journey takes  =  of an hour = 15 minutes.\r\n" );
document.write( "\r\n" );
document.write( " 2-nd half of the journey takes  of an hour = 25 minutes.\r\n" );
document.write( "\r\n" );
document.write( " Total travel time is the sum 15 minutes + 25 minutes = 40 minutes, showing my answer/solution is CORRECT.\r\n" );
document.write( " \r
\n" );
document.write( "\n" );
document.write( "Solved.\r
\n" );
document.write( "
\n" );
document.write( "
\n" );
document.write( "\n" );
document.write( "The answer \" 24 kilometers \" from the textbook is W R O N G.\r
\n" );
document.write( "
\n" );
document.write( "
\n" );
document.write( "\n" );
document.write( " \n" );
document.write( " |