document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=233646>Question 233646</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 8.46 A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on<BR>\n" );
document.write( "a very accurate scale. <BR>\n" );
document.write( "The results in grams were 3.087 3.131 3.241 3.241 3.270 3.353 3.400 3.411 3.437 3.477\r<BR>\n" );
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document.write( "(a) Construct a 90 percent confidence interval for the true mean weight. (b) What sample size<BR>\n" );
document.write( "would be necessary to estimate the true weight with an error of ± 0.03 grams with 90 percent confidence?\r<BR>\n" );
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document.write( "(c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during<BR>\n" );
document.write( "manufacture. (Data are from a project by MBA student Henry Scussel.)<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 #172464 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=172464\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 8.46 A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on<BR>\n" );
document.write( "a very accurate scale. <BR>\n" );
document.write( "The results in grams were 3.087 3.131 3.241 3.241 3.270 3.353 3.400 3.411 3.437 3.477 <BR>\n" );
document.write( "(a) Construct a 90 percent confidence interval for the true mean weight.<BR>\n" );
document.write( "sample mean = 3.3048 ; sample std = 0.13199<BR>\n" );
document.write( "standard error: 1.645*0.13199/Sqrt(10) = 0.06866<BR>\n" );
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document.write( "90% CI: 3.3048-0.06866 < u < 3.3048+0.06866<BR>\n" );
document.write( "90% CI:3.23614 < u < 3.37346<BR>\n" );
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document.write( "(b) What sample size would be necessary to estimate the true weight with an error of ± 0.03 grams with 90 percent confidence?<BR>\n" );
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document.write( "n = [1.645*0.13199/0.03]^2 = 7.24^2 = 52.38<BR>\n" );
document.write( "Round up to get n = 53<BR>\n" );
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document.write( "(c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture. (Data are from a project by MBA student Henry Scussel.)<BR>\n" );
document.write( "I'll leave that to you.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.\r<BR>\n" );
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