The Used Lightbulb
The lifetime of a certain lightbulb is exponentially distributed with mean 1000 hours. You find one in a hallway that has been burning continuously for exactly 1000 hours and is still working. What is the expected total lifetime of this bulb, measured in hours from when it was first switched on?
Related problems & prerequisites
Worth solving first
- The Gap Between Two Lifetimes 4.0/10
- Finishing in Order 4.0/10
- Twice as Long 3.0/10
Source: Classic exponential-distribution exercise in wide circulation; no traceable original source. Statement written for AxiomIQ.