The length of time for students to complete a 1-hour timed standardized mathematics test has a probability density function f(t) = 1.5t^2 + t, 0 ≤ t ≤ 1, where t is the time in hours. (Round your answers to three decimal places.)
(a) Find the probability that the time it takes a randomly selected student to complete the test is more than 51 minutes.
(b) Find the probability that the time it takes a randomly selected student to complete the test is more than 15 minutes given that it is less than 51 minutes.