The Percent Copper in Brass

I have a question for AP Chem about the lab “Percent Copper in Brass.””In order to accommodate the range of possible [Cu 2 ] concentrations that may be obtained by dissolving brass it’s recommended that the calibration curve extend from approximately 0.05 M to 0.4 M. Estimate the absorbance of standard solutions containing 0.05 M 0.1 M 0.2 M and 0.4 M copper(II) nitrate at the selected wavelength.”