document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=181362>Question 181362</A>: <I><SPAN STYLE=\"word-break: break-all;\"> im now sure i need HELP PLEASE<BR>\n" );
document.write( "If the illumination of a book 9m from a lamp is 150 lumens/m^2 find the illumination of the book 3m closer to the lamp...<BR>\n" );
document.write( "I got 225 lm/m^2????????????????????? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #135980 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><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=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=135980\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> im now sure i need HELP PLEASE<BR>\n" );
document.write( "If the illumination of a book 9m from a lamp is 150 lumens/m^2 find the illumination of the book 3m closer to the lamp...<BR>\n" );
document.write( "I got 225 lm/m^2?????????????????????<BR>\n" );
document.write( "--------------------<BR>\n" );
document.write( "It's an inverse square relationship, common in nature.<BR>\n" );
document.write( "i = k/d^2 (illumination = a constant/the distance squared)<BR>\n" );
document.write( "150 = k/9^2<BR>\n" );
document.write( "k = 150*81 = 12150<BR>\n" );
document.write( "------------<BR>\n" );
document.write( "@ 6 meters:<BR>\n" );
document.write( "i = 12150/6^2 = 12150/36<BR>\n" );
document.write( "i = 337.5 lm/m^2<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );