document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1207908>Question 1207908</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A report in the Child Trends DataBase indicated that, in 1996, 22.2% of twelfth grade students reported daily use of cigarettes. In 2006, 12.2% of twelfth grade students reported daily use of cigarettes.\r<BR>\n" );
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document.write( "(a) Write a linear equation that relates the percent y of twelfth grade students who smoke cigarettes daily to the number x of years after 1996.\r<BR>\n" );
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document.write( "NOTE: I think the two points needed for this problem are (1996, 0.222) and <BR>\n" );
document.write( "(2006, 0.122)\r<BR>\n" );
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document.write( "I can then find the slope and use the point-slope formula to find my equation. \r<BR>\n" );
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document.write( "Am I right? \r<BR>\n" );
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document.write( "(b) Find the intercepts of the graph of your equation.\r<BR>\n" );
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document.write( "(c)Do the intercepts have any meaningful interpretation?\r<BR>\n" );
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document.write( "(d) Use your equation to predict the percentage for the year 2016. Is this result reasonable? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #846044 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52781)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=846044\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .\r<BR>\n" );
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document.write( "<PRE STYLE=\"white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;\">\r\n" );
document.write( "If you read the problem attentively, you will see these words \"the number x of years after 1996\"  there.\r\n" );
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document.write( "These words mean that you should write 0 for 1996 and 10 for 2006.\r\n" );
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document.write( "After that, you can continue your solution in the formal way.\r\n" );
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document.write( "The problem can be easily solved mentally without using complicated interpolation-extrapolation formula.\r\n" );
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document.write( "From the problem, the time interval is 10 years; the difference in percentage is 22.2-12.2 = 10 percents total.\r\n" );
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document.write( "It tells us that the average decreasing rate is 1 percent per year.\r\n" );
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document.write( "So we write  y = 22.2 - x  for percents, where  x  represents years after 1996 to 2006.\r\n" );
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document.write( "And it is all what we need. We get the results by the simplest way.\r<BR>\n" );
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