document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=150449>Question 150449</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I found where someone answered this problem...Stan H.  However, I didn't understand how he got the answer.  I really would like to understand the how to on this since this is a statics class and I have more to do. On the random sample question I know that I needed to get the sample mean..standard deviation, t value and sample size.  I have posted it below. Then I have to use the forumla x ± t s&#8730;n....(that is suppose to be a square root sign with the s over the n.)  X is the sample mean...and t is the t value...but then I'm not sure where to place the standard deviation or the sample size... are they the s or the n...then which part of the equation do you do first and what does this little sign mean ±?  This part is only for section A.  I have no idea how to work through section b.  And yes, I understand c with no problem.  :)  I really appreciate in advance any help!  \r<BR>\n" );
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document.write( "3.3048 is the sample mean= x with line over it.<BR>\n" );
document.write( "1.32 is the standard deviation<BR>\n" );
document.write( "1.833 is the “t” value**<BR>\n" );
document.write( "10 is the sample size\r<BR>\n" );
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document.write( "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 Page 309 \r<BR>\n" );
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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" );
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document.write( "(a) Construct a 90 percent confidence interval for the true mean weight. <BR>\n" );
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" );
document.write( "(c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture. <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 #110448 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=110448\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 3.3048 is the sample mean= x with line over it.<BR>\n" );
document.write( "1.32 is the standard deviation<BR>\n" );
document.write( "1.833 is the “t” value**<BR>\n" );
document.write( "10 is the sample size \r<BR>\n" );
document.write( "\n" );
document.write( "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 Page 309 <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( "A confidence interval looks like (x-bar-E < u < x-bar+E)<BR>\n" );
document.write( "E is the margin of error and equals t * [s/sqrt(n)]<BR>\n" );
document.write( "Your E = 1.833[1.32/sqrt(10)] = 0.76513...<BR>\n" );
document.write( "Your 90% CI is (3.3048-0.76513 < u < 3.3048+0.76513)<BR>\n" );
document.write( "This can be simplified: (2.5397 < u < 4.06993)<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" );
document.write( "Using the formula for E you can solve for \"n\":<BR>\n" );
document.write( "E = t * [s/sqrt(n)]<BR>\n" );
document.write( "sqrt(n) = t*s/E<BR>\n" );
document.write( "n = [ts/E]^2<BR>\n" );
document.write( "Your problem:<BR>\n" );
document.write( "n = [1.833*1.32/0.03] = 6504 when rounded down<BR>\n" );
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document.write( "(c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture. <BR>\n" );
document.write( "machinery error, weighing variation, mix inconsistency, etc.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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