The following results were obtained when each of a series of standard silver solutions was analyses by flame atomic-absorption spectrometry. Concentration, ng mL 1 Absorbance 10 15 20 25 30 0.003 0.127 0.251 0.390 0.498 0.625 0.763 Determine (present answers using both manual calculations and Excel generated result) the slope and intercept of the calibration plot, and their confidence limits at 95%.