Let $T \in \text{Exp}(\theta)$ be an D214: Exponential random positive real number.
Let $t \in \mathbb{R}$ be a D993: Real number.
Let $t \in \mathbb{R}$ be a D993: Real number.
Then
\begin{equation}
\mathbb{P}(T \leq t)
= \left( 1 - e^{- \theta t} \right) I_{[0, \infty)} (t)
\end{equation}