document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1201062>Question 1201062</A>: <I><SPAN STYLE=\"word-break: break-all;\"> (a) Find the minimal sample size required so that for a confidence interval, the maximal margin of error is \r<BR>\n" );
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document.write( "(b) Based on this sample size and the distribution, can we assume that the distribution is approximately normal? Explain.<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #840416 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=840416\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> You are missing some information, but here is the approach.<BR>\n" );
document.write( "error = z*sqrt(p*(1-p))/n<BR>\n" );
document.write( "suppose z=1.96 for 95% CI<BR>\n" );
document.write( "and suppose p=0.4 and n=50<BR>\n" );
document.write( "then error=1.96*(sqrt(.24/50)<BR>\n" );
document.write( "=0.1358 <BR>\n" );
document.write( "np and n(1-p) are both more than 10 so yes can assume normality.\r<BR>\n" );
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document.write( "note that the error for probability around 50% is about 1/sqrt(n).<BR>\n" );
document.write( "This comes from using z=2 and p=0.5,  Very useful to know this.  </SPAN>\n" );
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