The weights of all the boxes of corn flakes filled by a machine are normally distributed, with a mean weight of 16.5 ounces and a standard deviation of 0.4 ounce. What percent of the boxes will have the following weights? (Round your answers to one decimal place.)
(a) weigh less than 16 ounces
%
(b) weigh between 15.5 ounces and 17.5 ounces
%