題組內容

3. Let $Y_1 < Y_2 < Y_3$ be the order statistics of a random sample of size $n = 3$ from the exponential distribution with p.d.f. $f(x) = e^{-x}$, $0 < x < \infty$.

(1) Find the p.d.f. of the sample median \( Y_{2} \). (5%)