f(x, y)=\left\{\begin{array}{ll} \frac{2}{3}(x+2 y), & 0 \leq x \leq 1,0 \leq y \leq 1 \\ 0, & \text { elsewhere } \end{array}\right. (a) Find the marginal density of X. (b) Find the marginal density of Y. (c) Find the probability that the drive-through facility is busy less than one-half of the time.

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