document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=177902>Question 177902</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A random sample of 10 miniature Tootsie Rolls was taken from a bag.  Each piece was weighed on a very accurate scale.  The results in grams were:\r<BR>\n" );
document.write( "\n" );
document.write( "3.087 3.131 3.241 3.241 3.270 3.353 3.400 3.411 3.437 3.477\r<BR>\n" );
document.write( "\n" );
document.write( "(a)	Construct a 90 percent confidence interval for the true mean weight. \r<BR>\n" );
document.write( "\n" );
document.write( "(b) What sample size would be necessary to estimate the true weight with an error (+ or -) 0.03 grams with 90 percent confidence?  \r<BR>\n" );
document.write( "\n" );
document.write( "(c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture.   </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #133090 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=133090\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were: <BR>\n" );
document.write( "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( "x-bar = (sum of the number)/10  = 3.308<BR>\n" );
document.write( "E = z = 1.645*0.1399/sqrt(10) = 0.0728<BR>\n" );
document.write( "-------<BR>\n" );
document.write( "90% CI; 3.308-0.0728-0.0728 < u < 3.308+0.0728<BR>\n" );
document.write( "----------------------------------------------------------------<BR>\n" );
document.write( "(b) What sample size would be necessary to estimate the true weight with an error (+ or -) 0.03 grams with 90 percent confidence? <BR>\n" );
document.write( "n = [z*s/E]^2<BR>\n" );
document.write( "n = [1.645*0.1399/0.03]^2 = 7.67^2 is appox 50<BR>\n" );
document.write( "-----------------------------\r<BR>\n" );
document.write( "\n" );
document.write( "(c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture.<BR>\n" );
document.write( "I'll leave that to your imagination.<BR>\n" );
document.write( "========================================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );