A privately owned liquor store operates both a drive-n facility and a walk-in facility. On a randomly selected day, let X and Y, respectively, be the proportions of the time that the drive-in and walk-in facilities are in use, and suppose that the joint density function of these variables is
a) Find the marginal density of X.
b) Find the marginal density of Y.
c) Find the probability that the drive-in facility is busy less than one-half of the time.