A survey was conducted to measure the height of men. In the survey, respondents were grouped by age. In the 20-29 age group, the heights were normally distributed, with a mean of 68.9 inches and a standard deviation of 4.0 inches. A study participant is randomly selected.
(a) Find the probability that his height is less than 66 inches.
(b) The probability that the participant selected at random is less than 66 inches is ____.
Round to four decimal places as needed.