Highlight a spreadsheet cell to hold 'x', the result of the final equation (cell C12, labeled B in Figure 5). Click in the equation area (labeled C, figure 5) Type an equal sign and then a parentheses Click in the cell representing 'y' in your equation (cell B12 in Figure 5) to put this cell label in your equation Finish typing your equation Note: If your equation differs for the one in this example, use your equation Duplicate your equation for the other unknown. Highlight the original equation cell (C12 in Figure 5) and the cell below it (C13) Using the R-squared coefficient calculation to estimate fit Double-click on the trendline, choose the Options tab in the Format Trendlines dialogue box, and check the Display r-squared value on chart box. Your graph should now look like Figure 6. Note the value of R-squared on the graph. The closer to 1.0, the better the fit of the regression line. That is, the closer the line passes through all of the points. Figure 6 . Now lets look at another set of data done for this lab (Figure 7). Notice that the equation for the regression line is different than is was in Figure 6. A different equation would calculate a different concentration for the two unknowns. Which regression line better represents the 'true' relationship between absorption and concentration? Look at how closely the regression line passes through the points in Figure 7. Does it seem to 'fit' as well as it