document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=326968>Question 326968</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I am still having trouble on this can some one please make it a little clearer for me on how to get the answer to this. i am having trouble showing the work on this.\r<BR>\n" );
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document.write( "1.  Construct a scatter plot using excel for the given data. Determine whether there is a positive linear correlation, negative linear correlation, or no linear correlation. Complete the table and find the correlation coefficient r. (References: example 1 - 4 pages 498 - 500; end of section exercises 15 - 22 pages 508 - 509)  \r<BR>\n" );
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document.write( "The data below are the number of absences and the final grades of 9 randomly selected students from a statistics class. \r<BR>\n" );
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document.write( "Absences, x	4	7	10	8	13	6	19	12	9<BR>\n" );
document.write( "Final grade, y	99	87	81	83	72	93	56	77	83\r<BR>\n" );
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document.write( "a:  Scatter plot  (3.5 points)\r<BR>\n" );
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document.write( "b:  Type of correlation (positive linear correlation, negative linear correlation, or no linear correlation)  (2.5 points)\r<BR>\n" );
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document.write( "c:  Complete the table and find the correlation coefficient r.<BR>\n" );
document.write( "(6 points)<BR>\n" );
document.write( "x	y	xy	x2	y2<BR>\n" );
document.write( "4	99			<BR>\n" );
document.write( "7	87			<BR>\n" );
document.write( "10	81			<BR>\n" );
document.write( "8	83			<BR>\n" );
document.write( "13	72			<BR>\n" );
document.write( "6	93			<BR>\n" );
document.write( "19	56			<BR>\n" );
document.write( "12	77			<BR>\n" );
document.write( "9	83			<BR>\n" );
document.write( "				<BR>\n" );
document.write( "Use the last row of the table to show the column totals.<BR>\n" );
document.write( "n = 9<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 #234226 by </B><A HREF=/tutors/aboutme.mpl?userid=Fombitz><B>Fombitz(32388)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Fombitz><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/cgi-bin/show-face.mpl?user=Fombitz><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=234226\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> a) Enter the data into two columns in an Excel spreadsheet.<BR>\n" );
document.write( "Highlight the columns and hit the Chart Wizard button.<BR>\n" );
document.write( "Choose scatterplot.\r<BR>\n" );
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document.write( "b) Looking at the scatterplot, you can make a good guess about the correlation. <BR>\n" );
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document.write( "To get an actual <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=r%5E2 ALIGN=MIDDLE  ALT=\"r%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" > value do the following.<BR>\n" );
document.write( "Once you finish the chart, right click on a data point. <BR>\n" );
document.write( "Choose \"Add trendline\".<BR>\n" );
document.write( "Under Type tab, choose Linear.<BR>\n" );
document.write( "Go to the Options tab.<BR>\n" );
document.write( "Click \"Display equation on Chart\" and \"Display R-sqaured value on Chart\".<BR>\n" );
document.write( "Read the <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=R%5E2 ALIGN=MIDDLE  ALT=\"R%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" > value off of the chart. \r<BR>\n" );
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document.write( "c) X values in column 1, rows 1-9<BR>\n" );
document.write( "Y values in column 2, rows 1-9<BR>\n" );
document.write( "Find the average of the x values, xave=9.78.<BR>\n" );
document.write( "Find the average of the y values, yave=81.22.<BR>\n" );
document.write( "Generate a new column (column 3) equal to (x-9.78), in EXCEL the formula would be \"=A1-9.78\" for column 3, row 1, cell. Copy this formula down the column.\r<BR>\n" );
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document.write( "Generate a new column (column 4) equal to (y-81.22), in EXCEL the formula would be \"=B1-81.22\" for column 4, row 1, cell. Copy this formula down the column..\r<BR>\n" );
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document.write( "Generate a new column (column 5) equal to (x-9.78)^2, in EXCEL the formula would be \"=C1^2\" for column 5, row 1, cell. Copy this formula down the column.\r<BR>\n" );
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document.write( "Generate a new column (column 6) equal to (y-81.22)^2, in EXCEL the formula would be \"=D1^2.\" for column 6, row 1, cell. Copy this formula down the column.\r<BR>\n" );
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document.write( "Generate a new column (column 7) equal to (x-9.78)(y-81.22), in EXCEL the formula would be \"=C1*D1.\" for column 7, row 1, cell. Copy this formula down the column.\r<BR>\n" );
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document.write( "Sum the values for column 5 (SSXX), column 6 (SSYY), and column 7 (SSXY).<BR>\n" );
document.write( "Find the value of SSXY/SSXX, that is b the slope of the regression line. <BR>\n" );
document.write( "Find the value of SSXY/SSYY, call that b'.<BR>\n" );
document.write( "By definition, r^2=b*b'<BR>\n" );
document.write( "So then to find r, take the square root.\r<BR>\n" );
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document.write( "It's actually easier than it looks.<BR>\n" );
document.write( "As a check, you should get the <BR>\n" );
document.write( "SSXX=159.56<BR>\n" );
document.write( "SSYY=1233.56<BR>\n" );
document.write( "If not, there's a mistake somewhere.<BR>\n" );
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document.write( "For a more technical explanation, check out http://mathworld.wolfram.com/LeastSquaresFitting.html </SPAN>\n" );
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