Steel rods are manufactured with a mean length of 20 centimeter (cm). because of variability in the manufacturing process, the lengths of the rods are approximately normally distributed with a standard deviation of 0.07 cm. (a) what proportion of rods has a length less than 19.9 cm? (round to four decimal places as needed.) (b) any rods that are shorter than 19.85 cm or longer than 20.15 cm are discarded. what proportion of rods will be discarded? (round to four decimal places as