Question: The following analytical data were obtained for a spectrophotometric analysis:

Conc.(mg dm³) Absorbance

10 0.201, 0.194

25 0.495, 0.508

50 0.983, 1.009

100 1.964, 2.013

(i) compute r and r², and explain what their values indicate,

(ii) find the regression equation of absorbance on concentration,

(iii) predict the concentration , if the absorbance was 0.650.

(iv) plot the residuals from the regression analysis against the concentration. What does the resulting pattern indicate?