document.write( "Question 982361: On a journey of 100km, Jim travels at a certain speed for the first 60km, and then increases his speed by 15km/h for the remainder. If the whole journey takes 2 hours, find his two speeds.
\n" );
document.write( "I'm in year 10, and this is an A-standard question which neither of my parents nor I could solve. \n" );
document.write( "
Algebra.Com's Answer #603178 by josgarithmetic(39630) ![]() You can put this solution on YOUR website! Uniform Rates for Travel, RT=D relates rate, time, distance.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Let r be the unknown rate for the first part; \n" ); document.write( "let d be the unknown distance of the second part;\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "___________________rate_____________time_____________distance \n" ); document.write( "part1_______________r_______________(___)_____________60 \n" ); document.write( "part2______________r+15_____________(___)_____________d \n" ); document.write( "TOTALS_______________________________2________________100\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Form expressions for the missing time quantities from the basic idea \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "___________________rate_____________time_____________distance \n" ); document.write( "part1_______________r_______________60/r______________60 \n" ); document.write( "part2______________r+15_____________d/(r+15)___________d \n" ); document.write( "TOTALS_______________________________2________________100\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Note that the distance sum arrangement will give the unknown part2 distance. \n" ); document.write( "60+d=100 \n" ); document.write( "d=100-60 \n" ); document.write( "d=40 \n" ); document.write( "and you can adjust the tabulated information:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "___________________rate_____________time_____________distance \n" ); document.write( "part1_______________r_______________60/r______________60 \n" ); document.write( "part2______________r+15_____________40/(r+15)__________40 \n" ); document.write( "TOTALS_______________________________2________________100\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The total time will give an equation in the single variable, r. \n" ); document.write( " \n" ); document.write( "This can be partly simplified to \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Can you solve this equation for r ?\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "--- \n" ); document.write( "The algebra steps give a factorable quadratic equation, making the final answer apparent. \n" ); document.write( " |