document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1194708>Question 1194708</A>: <I><SPAN STYLE=\"word-break: break-all;\"> You want to obtain a sample to estimate how much parents spend on their kids birthday parties. Based on previous study, you believe the population standard deviation is approximately σ=71.2 dollars. You would like to be 99% confident that your estimate is within 1.5 dollar(s) of average spending on the birthday parties. How many parents do you have to sample?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #826962 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=826962\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 99% CI is z(0.995)*sigma/sqrt(n)=1.5<BR>\n" );
document.write( "z=2.576<BR>\n" );
document.write( "so 2.576*71.2/sqrt(n)=1.5<BR>\n" );
document.write( "square both sides and move the n over<BR>\n" );
document.write( "33639.67=2.25 n<BR>\n" );
document.write( "n=14,951 </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );