The objective is to design a compound spur gear train which uses the minimum number of stages required to achieve a gear ratio of -400 : 1, using gears with a 20 pressure angle and Pa = 48 in. The design must meet the following basic requirements: - All gears must mesh without interference (Nmin 2 18). - The gear train must have gear ratios equal to or lower than 5 at all stages. - The design must provide an output rotation in the oppo site direction as its input. (a) Provide a rough sketch of the final designed gear train. (10 PTS) (b) Determine the number of teeth for each gear. (10 PTS) (c) Determine the pitch diameter of the largest and the smallest gears in the gear train. (10 PTS)