document.write( "Question 1057577: A boat travels 30 miles up the river in the same amount of time it takes to travel 46 miles down the same river. If the current is 4 miles per hour, what is the speed of the boat in still water? \n" ); document.write( "

Algebra.Com's Answer #672617 by ikleyn(52781) $\"\"$ $\"About$

You can put this solution on YOUR website!
.
\n" ); document.write( "A boat travels 30 miles up the river in the same amount of time it takes to travel 46 miles down the same river.
\n" ); document.write( "If the current is 4 miles per hour, what is the speed of the boat in still water?
\n" ); document.write( "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "

\r\n" );
document.write( "The governing equation is\r\n" );
document.write( "\r\n" );
document.write( " =    (\"time\" equation; u is the boat speed in still water)\r\n" );
document.write( "\r\n" );
document.write( "Cross-multiply:\r\n" );
document.write( "\r\n" );
document.write( "30*(u+4) = 46(u-4),\r\n" );
document.write( "\r\n" );
document.write( "30u + 120 = 46u - 184,\r\n" );
document.write( "\r\n" );
document.write( "120 + 184 = 46u - 30u,\r\n" );
document.write( "\r\n" );
document.write( "304 = 16u  --->  u =  = 19.\r\n" );
document.write( "\r\n" );
document.write( "Answer. The boat speed in still water is 19 mph.\r\n" );
document.write( "

\r
\n" ); document.write( "\n" ); document.write( "It is a typical Upstream and Downstream round trips word problem.\r
\n" ); document.write( "\n" ); document.write( "You can find similar fully solved problems on upstream and downstream round trips with detailed solutions in lessons \r
\n" ); document.write( "\n" ); document.write( "    - Wind and Current problems \r
\n" ); document.write( "\n" ); document.write( "    - More problems on upstream and downstream round trips \r
\n" ); document.write( "\n" ); document.write( "    - Selected problems from the archive on the boat floating Upstream and Downstream \r
\n" ); document.write( "\n" ); document.write( "in this site.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "See especially the last of these three lessons, Problem 3.
\n" ); document.write( "It is exactly your sample/prototype.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Read them attentively and learn how to solve this type of problems once and for all.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Also, you have this free of charge online textbook in ALGEBRA-I in this site\r
\n" ); document.write( "\n" ); document.write( "    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "The referred lessons are the part of this textbook under the section \"Word problems\", the topic \"Travel and Distance problems\".\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

\n" );