A 5.0 mL aliquot of a stock tryptophan solution was diluted by adding 95 mL of water. The absorbance of that diluted solution was measured at 280 nm as 0.055 absorbance units. What is the concentration of the stock (original) solution? Hint: Make sure to calculate the dilution factor. (Molar extinction coefficient = 5579 cm-1 M-1.