document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=863039>Question 863039</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Please help me in answering this problem: <BR>\n" );
document.write( "The unit measure for atmospheric pressure is KPa (Kilo-Pascals). At sea level the standard atmospheric pressure is 101.3 KPa. For every 1000 feet increase in altitude atmospheric pressure decreases by 1.8 KPa. <BR>\n" );
document.write( "What is the atmospheric pressure at 50,000 feet?\r<BR>\n" );
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document.write( "I have tried to answer the question, my understanding to the question is what is the value of t 50,000 and the common difference d is 1000 but I didn't know if I should consider the first term (a)= 101.3 or 101.3 - 1.8 = 99.5 KPa\r<BR>\n" );
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document.write( "Thank you </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #520294 by </B><A HREF=/tutors/aboutme.mpl?userid=richwmiller><B>richwmiller(17219)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=richwmiller><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=richwmiller><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=520294\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> At sea level, the height is 0 and the pressure is 101.3<BR>\n" );
document.write( "At 1000 ft, the height is 1000 and the pressure is 99.5<BR>\n" );
document.write( "The first time we lose 1.8 is at 1000 ft or 1<BR>\n" );
document.write( "(0,101.3)<BR>\n" );
document.write( "(1, 99.5)<BR>\n" );
document.write( "(2, 97.7)<BR>\n" );
document.write( "So we lose 1.8 for each and every 1<BR>\n" );
document.write( "The common difference is -1.8 for every 1000 ft which we will consider 1<BR>\n" );
document.write( "The first time we lose 1.8 is at 1000 ft or 1<BR>\n" );
document.write( "we lose 1.8 for every 1000 ft<BR>\n" );
document.write( "If you work out the slope and y intercept<BR>\n" );
document.write( "y = 101.3-1.8x<BR>\n" );
document.write( "y=101.3-1.8*50<BR>\n" );
document.write( "y=11.3 KPa at 50000 ft\r<BR>\n" );
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document.write( "Your problem stems from starting with 0 at sea level and not 1000<BR>\n" );
document.write( "The linear equation is still y = 101.3-1.8x if we use the points (1, 99.5) and<BR>\n" );
document.write( "(2, 97.7) where x=50 and y=11.3<BR>\n" );
document.write( "An = a1 + (n - 1)d<BR>\n" );
document.write( "A50 = 99.5 -1.8(49)<BR>\n" );
document.write( "We still get 11.3 at 50000<BR>\n" );
document.write( "A50=11.3 KPa<BR>\n" );
document.write( "so A1 = 99.5 and the difference is -1.8\r<BR>\n" );
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