document.write( "Question 1167923: One roofer can put a new roof on a house three times faster than another. Working together they can roof a house in 5 days. How long would it take the faster roofer working alone? \n" ); document.write( "
Algebra.Com's Answer #792515 by Theo(13342)![]() ![]() You can put this solution on YOUR website! rate * time = quantity.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "let x = the rate of the slower roofer.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "then 3x = the rate of the faster roofer.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "when they work together their rates are additive and they can roof a house in 5 days.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "quantity = 1 roof\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "formula becomes:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(x + 3x) * 5 = 1 \n" ); document.write( "combine like terms to get: \n" ); document.write( "4x * 5 = 1 \n" ); document.write( "simplify to get: \n" ); document.write( "20x = 1 \n" ); document.write( "solve for x to get: \n" ); document.write( "x = 1/20\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that's the rate of the slower roofer.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the rate of the roofer is 3 times that = 3/20 of the job per day.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "when the faster roofer is working alone, the equation becomes:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "3/20 * time = 1\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "solve for time to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "time = 20/3\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the faster roofer, working alone, can roof a house in 20/3 days.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that would be 6 and 2/3 days.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that should be your answer. *****\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "to go a few steps further, .....\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "when the slower roofer works alone, the formula becomes:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "1/20 * time = 1\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "solve for time to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "time = 20 days.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the faster roofer completes the job in 6 and 2/3 days, working alone. \n" ); document.write( "the slower roofer completes the job in 20 days, working alone.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "it takes the slower work 3 times as long to complete the job as the faster worker.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that's because the faster worker is 3 times as fast as the slower worker.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "everything checks out.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your solution is good. \n" ); document.write( " \n" ); document.write( " |