This is an EXCEL question.

8. The accompanying table shows the calibration data for the chemical analysis of silica; X is the known amount of silica and Y is the absorbance of the solution. An unknown sample had an absorbance value of 0.242. Find the amount of silica in the unknown and give the 95% confidence limits. 0.060 Y 0.000 0.032 0.020 0.135 0.040 0.185 0.080 0.359 0.100 0.435 0.120 0.511 0.268