document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1077781>Question 1077781</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 9.2 #16<BR>\n" );
document.write( "People were polled on how many books they read the previous year. Initial survey results indicate that s=17.7 books. Complete parts &#8203;(a) through &#8203;(d) below.\r<BR>\n" );
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document.write( "a) How many subjects are needed to estimate the mean number of books read the previous year within four books with 95&#8203;% &#8203;confidence?\r<BR>\n" );
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document.write( "b) How many subjects are needed to estimate the mean number of books read the previous year within 2 books with 95&#8203;% &#8203;confidence?\r<BR>\n" );
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document.write( "this confidence level requites how many subjects?\r<BR>\n" );
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document.write( "c) how many subjects are needed to estimate the mean number of books read the previous year within four books with 9% confidence? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #692284 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=692284\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> interval is 1.96*s/sqrt(n).  I will use z, as I suspect n is large.  If not, I will iterate with t.<BR>\n" );
document.write( "1.96*17.7/sqrt(n)=4<BR>\n" );
document.write( "n=75.22 when squaring and rearranging.<BR>\n" );
document.write( "Will use t=2<BR>\n" );
document.write( "[2*17.7/4]^2=78.32 or 79. <BR>\n" );
document.write( "This has a t=1.99<BR>\n" );
document.write( "n=78<BR>\n" );
document.write( "with 2 books, this will be a much higher sample size<BR>\n" );
document.write( "313.29, round to 314, and z is used here.<BR>\n" );
document.write( "For the  last, I am going to assume 99% is meant.<BR>\n" );
document.write( "use 2.576 for z<BR>\n" );
document.write( "129.93 or 130 books. </SPAN>\n" );
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