document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=186937>Question 186937</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I need help in statistics. Can someone help me with this? Thank you!\r<BR>\n" );
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document.write( "A sample of 20 pages was taken without replacement from the 1,591-page phone directory Ameritech Pages Plus Yellow Pages. On each page, the mean area devoted to display ads was measured (a display ad is a large block of multicolored illustrations, maps, and text). The data (in<BR>\n" );
document.write( "square millimeters) are shown below:<BR>\n" );
document.write( "0 260 356 403 536 0 268 369 428 536<BR>\n" );
document.write( "268 396 469 536 162 338 403 536 536 130<BR>\n" );
document.write( "(a) Construct a 95 percent confidence interval for the true mean.<BR>\n" );
document.write( "(b) Why might normality be an issue here? <BR>\n" );
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( "(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 #140126 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=140126\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A sample of 20 pages was taken without replacement from the 1,591-page phone directory Ameritech Pages Plus Yellow Pages. On each page, the mean area devoted to display ads was measured (a display ad is a large block of multicolored illustrations, maps, and text). The data (in<BR>\n" );
document.write( "square millimeters) are shown below:<BR>\n" );
document.write( "0 260 356 403 536 0 268 369 428 536<BR>\n" );
document.write( "268 396 469 536 162 338 403 536 536 130<BR>\n" );
document.write( "(a) Construct a 95 percent confidence interval for the true mean.<BR>\n" );
document.write( "Sample mean = 346.5; Sample standard deviation = 170.38<BR>\n" );
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document.write( "E = 2.086 = 79.47<BR>\n" );
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document.write( "95% CI: 346.5-79.47 < u < 346.5+79.47<BR>\n" );
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document.write( "(b) Why might normality be an issue here?<BR>\n" );
document.write( "The sample is limited to a single source and may not be representative<BR>\n" );
document.write( "of the population of yellow pages.<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( "n = [z*s/E]^2<BR>\n" );
document.write( "n = [2.58.96*170.38/E]^2 = ?<BR>\n" );
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document.write( "Comment: Your posting has garbled the value of \"E\".<BR>\n" );
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document.write( "(d) If this is not a reasonable requirement, suggest one that is.<BR>\n" );
document.write( "??<BR>\n" );
document.write( "Don't know the answer to c so I don't know the answer to d.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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