document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=194912>Question 194912</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 0									<BR>\n" );
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document.write( "(a) Construct a 95 percent confidence interval for the true mean.									<BR>\n" );
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document.write( "(b) Why might normality be an issue here?									<BR>\n" );
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document.write( "(c) What sample size would be needed to obtain an error of ±10 square millimeters with 99 percent confidence?									<BR>\n" );
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document.write( "(d) If this is not a reasonable requirement, suggest one that is. 									<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 #146248 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=146248\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 260 <BR>\n" );
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document.write( "Hopefully you can find the mean (x-bar) and the <BR>\n" );
document.write( "standard deviation (s), which is needed to <BR>\n" );
document.write( "calculate the standard error (E).<BR>\n" );
document.write( "Do that first then attack the questions below.<BR>\n" );
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document.write( "(a) Construct a 95 percent confidence interval for the true mean. <BR>\n" );
document.write( "x-bar-E < u < x-bar+E<BR>\n" );
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document.write( "(b) Why might normality be an issue here? <BR>\n" );
document.write( "I'll leave that to you.<BR>\n" );
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document.write( "(c) What sample size would be needed to obtain an error of ±10 square millimeters with 99 percent confidence?<BR>\n" );
document.write( "Since E = zs/sqrt(n)<BR>\n" );
document.write( "sqrt(n) = zs/E<BR>\n" );
document.write( "then n = [zs/E]^2<BR>\n" );
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document.write( "For a 95% C.I., z = 1.96<BR>\n" );
document.write( "You have figured out the sample standard deviation<BR>\n" );
document.write( "You are told that E = 10<BR>\n" );
document.write( "So  n = [1.96*s/10]^2\r<BR>\n" );
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document.write( "(d) If this is not a reasonable requirement, suggest one that is.<BR>\n" );
document.write( "If \"n\" seems too large you could reduce the confidence requirement,<BR>\n" );
document.write( "or increase the size of the error limit.<BR>\n" );
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document.write( "Get back to me if you need further help.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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