document.write( "Question 485321: It takes 7 people 8 hours to build 3 cars. How many hours will it take 2 people to build 1 car? Thank you! \n" ); document.write( "
Algebra.Com's Answer #331948 by Edwin McCravy(20065)\"\" \"About 
You can put this solution on YOUR website!
It takes 7 people 8 hours to build 3 cars. How many hours will it take 2 people to build 1 car? Thank you!
\n" ); document.write( "
\r\n" );
document.write( "It takes 7 people 8 hours to build 3 cars.\r\n" );
document.write( "\r\n" );
document.write( "It takes 1 person 7 times as long to build 3 cars as it does 7 people.\r\n" );
document.write( "\r\n" );
document.write( "Therefore it takes 1 person 7×8 or 56 hours to build 3 cars.\r\n" );
document.write( "\r\n" );
document.write( "It takes 1 person only \"1%2F3\" as long to build just 1 car as it takes\r\n" );
document.write( "for him to build 3 cars.\r\n" );
document.write( "\r\n" );
document.write( "Therefore it takes 1 person \"1%2F3\"×56 or \"56%2F3\" hours to build 1 car.\r\n" );
document.write( "\r\n" );
document.write( "It takes 2 people only half as long to build 1 car as it takes 1 person.\r\n" );
document.write( "\r\n" );
document.write( "Therefore it takes 2 people \"56%2F3\"×\"1%2F2\" or \"28%2F3\" or \"9%261%2F3\" hours to build 1 car. \r\n" );
document.write( "\r\n" );
document.write( "Or you can do it by this formula:\r\n" );
document.write( "\r\n" );
document.write( "\"%28W%5B1%5D%2AT%5B1%5D%29%2FJ%5B1%5D+=+%28W%5B2%5D%2AT%5B2%5D%29%2FJ%5B2%5D\"\r\n" );
document.write( "\r\n" );
document.write( "where \r\n" );
document.write( "\r\n" );
document.write( "W1 = the number of workers (or machines) in the 1st situation.\r\n" );
document.write( "W2 = the number of workers (or machines) in the 2nd situation.\r\n" );
document.write( "\r\n" );
document.write( "T1 = the number of time units (hours, days, etc) in the 1st situation.\r\n" );
document.write( "T2 = the number of time units (hours, days, etc) in the 2nd situation.\r\n" );
document.write( "\r\n" );
document.write( "J1 = the number of jobs done in the 1st situation.\r\n" );
document.write( "J2 = the number of jobs done in the 2nd situation.\r\n" );
document.write( "\r\n" );
document.write( "In your case \r\n" );
document.write( "\r\n" );
document.write( "W1 = 7, T1 = 8, J1 = 3\r\n" );
document.write( "W2 = 2, T2 = ???, J2 = 1\r\n" );
document.write( "\r\n" );
document.write( "Where T2 is the unknown, so we can substitute in the formula:\r\n" );
document.write( "\r\n" );
document.write( "\"%28W%5B1%5D%2AT%5B1%5D%29%2FJ%5B1%5D+=+%28W%5B2%5D%2AT%5B2%5D%29%2FJ%5B2%5D\"\r\n" );
document.write( "\r\n" );
document.write( "\"%287%2A8%29%2F3+=+%282%2AT%5B2%5D%29%2F1\"\r\n" );
document.write( "\r\n" );
document.write( "\"56%2F3+=+%282%2AT%5B2%5D%29%2F1\"\r\n" );
document.write( "\r\n" );
document.write( "Cross multiply:\r\n" );
document.write( "\r\n" );
document.write( "\"56=6T%5B2%5D\"\r\n" );
document.write( "\r\n" );
document.write( "\"56%2F6=T%5B2%5D\"\r\n" );
document.write( "\r\n" );
document.write( "\"28%2F3=T%5B2%5D\"\r\n" );
document.write( "\r\n" );
document.write( "\"9%261%2F3=T%5B2%5D\"\r\n" );
document.write( "\r\n" );
document.write( "or 9 hours and 20 minutes.\r\n" );
document.write( "\r\n" );
document.write( "Edwin
\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "
\n" );