document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1169717>Question 1169717</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 1)Suppose that thepopulation variance of the amount of cooldrink supplied by avending machine is known to be 115𝑚𝑙2\r<BR>\n" );
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document.write( "i)The machine  was  activated 61times,  and  the mean  amount  of  cooldrink supplied on each occasion was 𝑋̅. If the upper confidence limit for a 99% confidence level is 188.20. What is the value of the sample mean 𝑋̅?\r<BR>\n" );
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document.write( "ii)What sample size is requiredif the estimateis requiredto be within 1𝑚𝑙2of the true value with probability 0.95? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #794601 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=794601\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> sd=sqrt(115)=10.72 ml<BR>\n" );
document.write( "the half-interval for 99%CI is z*sigma/sqrt(n)=2.576*10.72/sqrt(61)=3.54<BR>\n" );
document.write( "therefore the mean is 188.20-3.54 or 184.66 ml\r<BR>\n" );
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document.write( "to be within 1 ml (not sure what the 2 means there); 115 ml^2 are appropriate units for variance, but ml is appropriate for the answer.<BR>\n" );
document.write( "1.96*10.72/sqrt(n)=1; sqrt (n)=21.0112, n=441.47 or 442\r<BR>\n" );
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document.write( "sample size is 442. </SPAN>\n" );
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