The lengths of lumber a machine cuts are normally distributed with a mean of 89 inches and a standard deviation of 0.4 inch. (a) What is the probability that a randomly selected board cut by the machine has a length greater than 89.15 inches? (b) A sample of 41 boards is randomly selected. What is the probability that their mean length is greater than 89.15 Inches? ' ' .- . (a) The probability is E]. (Round to four decimal places as needed.) 1 f: (b) The probability is E]. (Round to four decimal places as needed.) - r