P r ( − 1 ≤ X ≤ − 1 4 ) d x = ∫ − 1 − 1 / 4 f ( x ) d x = ∫ − 1 − 1 / 2 0 d x + ∫ − 1 / 2 − 1 / 4 1 d x = 1 / 4. {\displaystyle {\begin{aligned}\mathrm {Pr} \left(-1\leq X\leq -{\frac {1}{4}}\right)\;\mathrm {d} x&=\int _{-1}^{-1/4}f(x)\;\mathrm {d} x=\int _{-1}^{-1/2}0\;\mathrm {d} x+\int _{-1/2}^{-1/4}1\;\mathrm {d} x=1/4.\end{aligned}}}
