Bull's-eye Bob at a hunting range fires his rifle at a target 200 meters downrange. The bullet

Question:

Bull's-eye Bob at a hunting range fires his rifle at a target 200 meters downrange. The bullet moves horizontally from the rifle barrel with a speed of 400 m/s.
(a) How far does the bullet drop from a straight-line horizontal path by the time it reaches the target?
(b) To hit a bull's-eye why does Bob adjust his gunsight so the barrel points a bit upward when he aims at the target?