You are setting up a hanging drop vapour diffusion experiment in order to crystallize your protein. The concentration of protein in your protein solution is 7.6 mg/ml, and you are using 200 mM Ammonium sulfate in HEPES buffer (pH = 7.50) as both your precipitant and reservoir solution. Instead of mixing your drop 1:1 (μl protein : μl reservoir), you decide to mix it 4:1 (μl protein : μl reservoir).
What is the initial concentration of protein in your mixed drop at the beginning of the vapour diffusion experiment.