document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1157233>Question 1157233</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A researcher wishes to estimate the proportion of adults who have​ high-speed Internet access. What size sample should be obtained if she wishes the estimate to be within 0.04 with 90​% confidence if<BR>\n" );
document.write( "​(a) she uses a previous estimate of 0.32​?<BR>\n" );
document.write( "​(b) she does not use any prior​ estimates? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #780068 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=780068\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 90% CI is z*SE=0.04 for half-interval <BR>\n" );
document.write( "so 1.645*sqrt(.32*.68/n)=0.04<BR>\n" );
document.write( "and<BR>\n" );
document.write( "1.645*sqrt(.32*.68)/0.04=sqrt(n)\r<BR>\n" );
document.write( "\n" );
document.write( "square both sides<BR>\n" );
document.write( "n=368.02 or 369 rounding up\r<BR>\n" );
document.write( "\n" );
document.write( "when the estimates are unknown, use .5 as the most conservative\r<BR>\n" );
document.write( "\n" );
document.write( "1.645*sqrt*(.25)/0.04=sqrt (n)'<BR>\n" );
document.write( "n=422.8 or 423\r<BR>\n" );
document.write( "\n" );
document.write( "having a prior estimate that is further from 0.5 in either direction will lower the needed sample size. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );