2. A distribution of spherical silica particles has 3 sizes: 1/3 of diameter 1 micron, 1/3 of diameter 5 microns, and 1/3 of diameter 10 microns, with the fractions on a volume (or mass) basis. Compute the following for these particles: a) Sauter mean diameter b) the average based on number

3. For the particles of problem 2, compute the range of settling times in water, for a settling distance of 1 m, at 25 degrees C expected from this distribution, under dilute conditions such that isolated particle analysis applies.