Cylindrical fibers $10$m in diameter will be placed perpendicular to a gas stream that is moving at $3$ m$/$s$.$ The gas stream contains particles that are $5$m in diameter and the particle concentration is $3$ mg$/$m$3.$ Center$-$to$-$center spacing of the fibers equal to four fiber diameters. How many fibers in parallel must be used in a row in order to reach $95\%$ overall collection efficiency?