document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1155903>Question 1155903</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A study of 420,098 cell phone users found that 139 of them developed cancer of the brain or nervous system. Prior to this study of cell phone​ use, the rate of such cancer was found to be 0.0206​% for those not using cell phones. Complete parts​ (a) and​ (b).<BR>\n" );
document.write( "a. Use the sample data to construct a 95​% confidence interval estimate of the percentage of cell phone users who develop cancer of the brain or nervous system.<BR>\n" );
document.write( "nothing​%less thanpless than<BR>\n" );
document.write( "nothing​% </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #778593 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=778593\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> p hat=0.000331<BR>\n" );
document.write( "half-interval is z0.975*sqrt(p(1-p)/n), p=0.000331 and 1-p=0.999669<BR>\n" );
document.write( "=1.96*sqrt(0.0000331/420098)<BR>\n" );
document.write( "=0.0000281*1.96=0.055 se<BR>\n" );
document.write( "add and subtract from mean<BR>\n" );
document.write( "(.028%, .039%)<BR>\n" );
document.write( "Since 0.0206% is not in the interval can conclude there is a difference.<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );