15.2.4 One dimensional random variables and their characteristics

Problem: The lifespan of an electric lamp has an exponential distribution with a mathematical expectation of \( L \) hours. What is the possibility that the lamp will last from \( m_{1} \) to \( M_{1} \) hours if \[ L=76 ; m_{1}=75 ; M_{1}=109 \text {. } \]