A 30-ml sample of broth from a penicillin fermentation is filtered in the laboratory on a 3cm^2 filter at a pressure drop of 5 psi. The filtration time is 4.5 min. Previous studies have shown that Penicillium chrysogenum filter cake is compressible with s=0.5. If 500 litres of broth from a pilot- scale fermenter must be filtered in hour, what size filter is required if the pressure drop a) 10psi b) 5psi