document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=927121>Question 927121</A>: <I><SPAN STYLE=\"word-break: break-all;\"> In a random sample of 150 households with an Internet connection,33 said that they had changed their Internet service provider within the past six months.\r<BR>\n" );
document.write( "\n" );
document.write( "a)Finda99%confidence interval for the proportion of customers who changed their Internet service provider within the past six months. <BR>\n" );
document.write( "b)Find the sample size needed for a99% confidence interval to specify the proportion to within ±0.03.<BR>\n" );
document.write( "c)If no estimate of the proportion is available,how large should the sample be? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #562738 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=562738\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> In a random sample of 150 households with an Internet connection,33 said that they had changed their Internet service provider within the past six months.<BR>\n" );
document.write( " a)Finda99%confidence interval for the proportion of customers who changed their Internet service provider within the past six months.<BR>\n" );
document.write( "p-hat = 33/150 = 0.22<BR>\n" );
document.write( "ME = 2.5758sqrt[0.22*0.78/150] = 0.034 <BR>\n" );
document.write( "99% CI:: 0.22-0.034 < p < 0.22+0.034<BR>\n" );
document.write( "------------------------------------------- <BR>\n" );
document.write( "b)Find the sample size needed for a99% confidence interval to specify the proportion to within ±0.03.<BR>\n" );
document.write( "n = [2.5758/0.03]^2*0.22*0.78 = 1266 when rounded up<BR>\n" );
document.write( "------------------------<BR>\n" );
document.write( " c)If no estimate of the proportion is available,how large should the sample be?<BR>\n" );
document.write( "n = [2.5758/0.03]^2(1/2)^2 = 1843 when rounded up<BR>\n" );
document.write( "=============\r<BR>\n" );
document.write( "\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( "------------------  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );