Samples from a PUREX extraction were measured with a proportional counter in the alpha window. Samples of the same volume were taken from the aqueous and organic phases and evaporated. With the same counting time of 100 sec for samples and background, 400 counts were registered for the aqueous phase sample, 2500 for organic phase sample and 64 counts for the background. 

a) What are the net count rates of the organic and aqueous samples and their absolute and relative uncertainties? 

b) What is the distribution ratio (d = A sub organic/A sub aqueous) of the extracted alpha radionuclide with 95% confidence?