A pulp screen is fed with $50000$m$^3/$d of stock at $1\%$ consistency. The feed pulp has a long fibre fraction of $20\%$ and a shive content of $0\mathrm{.}5\%.$ The screen accept flow is at $0\mathrm{.}8\%$ consistency, with a long fibre fraction of $28\%$ and a shive content of $0\mathrm{.}1\%.$ The consistency of the stream is $1\mathrm{.}3\%.$ calculate the following screen performance characteristics compare the selectivity of the screen with respect to shoveives and long fibres