document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1208018>Question 1208018</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The time t that it takes to get to school varies inversely with your average speed s. \r<BR>\n" );
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document.write( "(a) Suppose that it takes you 40 minutes to get to school when your average speed is 30 miles per hour. Express the driving time to school in terms of average speed. \r<BR>\n" );
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document.write( "(b) Suppose that your average speed to school is 40 miles per hour. How long will it take you to get to school? </SPAN>\n" );
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document.write( "In the problem, speeds are in miles per hour and times are in minutes.<br><BR>\n" );
document.write( "In general, you can get into all kinds of trouble if you work a problem with mixed units.  It would be better mathematics if you change miles per hour to miles per minute, or change minutes to hours.<br><BR>\n" );
document.write( "However, in this simple problem, working with mixed units is okay.<br><BR>\n" );
document.write( "The way the problem is posed, you are apparently supposed to use the result from part (a) to find the answer to part (b).<br><BR>\n" );
document.write( "However, finding the answer to part (b) is trivial if you use the fact that, because of the inverse variation (using mixed units!), the product of the speed in miles per hour and the time in minutes is constant:<br><BR>\n" );
document.write( "30mph * 40 minutes = 40mph * x minutes<br><BR>\n" );
document.write( "30*40 = 40*x<br><BR>\n" );
document.write( "Trivially, the answer is 30 (minutes)<br><BR>\n" );
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