A continuous random variable XXX has PDF f(x)=e−xf(x) = e^{-x}f(x)=e−x for x≥0x \ge 0x≥0. What is P(X>2∣X>1)P(X > 2 | X > 1)P(X>2∣X>1)?
e−2e^{-2}e−2
e−1e^{-1}e−1
e−3e^{-3}e−3
1−e−11 - e^{-1}1−e−1