Answer:
1 time unit
Step-by-step explanation:
There is a 1 in 3 chance that the time until the bulb burns out is zero, and a 2 in 3 chance that the time is the average between 0 and 3 (since it is uniformly distributed). Therefore, the expected value for the time until it burns is:
The expected value of the time until the lightbulb burns out is 1 time unit.