The heights of pecan trees are normally distributed with a mean of 10 feet and a standard deviation of 2 feet. Show all work.

a. What is the probability that a randomly selected pecan tree is between 7 and 11 feet tall? (round the answer to 4 decimal places)                                                

b. Find the 40th percentile of the pecan tree height distribution. (round the answer to 2 decimal places)