document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=890812>Question 890812</A>: <I><SPAN STYLE=\"word-break: break-all;\"> where a is the altitude above sea level (in miles). If a city has an atmospheric pressure of 11.19 psi, what is its altitude? (Recall that 1 mi = 5,280 ft. Round your answer to the nearest foot.)<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #539311 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=539311\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> you need the formula for atmospheric pressure in terms of altitude.\r<BR>\n" );
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document.write( "the formula is normally shown as P = 14.7 * e^(-.21*a).\r<BR>\n" );
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document.write( "if your formula is different because they take 14.7 out to more decimal places, then you need to use what you are given instead.\r<BR>\n" );
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document.write( "P is the atmospheric pressure.<BR>\n" );
document.write( "a is the altitude in miles.\r<BR>\n" );
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document.write( "in your problem, P is given as 11.19 and you want to solve for a.\r<BR>\n" );
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document.write( "the equation becomes:\r<BR>\n" );
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document.write( "11.19 = 14.7 * e^(-.21*a)\r<BR>\n" );
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document.write( "divide both sides of this equation by 14.7 to get:\r<BR>\n" );
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document.write( "11.19 / 14.7 = e^(-.21*a)\r<BR>\n" );
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document.write( "take the natural log of both sides of this equation to get:\r<BR>\n" );
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document.write( "ln(11.19/14.7) = ln(e^(-.21*a)\r<BR>\n" );
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document.write( "since ln(e^(-.21*a) is equal to -.21*a*ln(e), your equation becomes:\r<BR>\n" );
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document.write( "ln(11.19/14.7) = -.21*a*ln(e)\r<BR>\n" );
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document.write( "since ln(e) = 1, your equation becomes:\r<BR>\n" );
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document.write( "ln(11.19/14.7) = -.21*a\r<BR>\n" );
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document.write( "divide both sides of this equation by -.21 to get:\r<BR>\n" );
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document.write( "ln(11.19/14.7)/-.21 = a\r<BR>\n" );
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document.write( "solve for a to get:\r<BR>\n" );
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document.write( "a = 1.299176... miles\r<BR>\n" );
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document.write( "since there are 5280 feet in a mile, then you get:\r<BR>\n" );
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document.write( "a = 6859.6495... feet which you can round to 6860 feet.\r<BR>\n" );
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