# Question: the probability density function of an exponentially distributed random variable...

###### Question details

The probability density function of an exponentially distributed random variable with mean 1/λ is λe^−λt for t≥0. Suppose the lifetime of a particular brand of light bulb follows an exponential distribution with a mean of 1000 hours. If a light fixture is equipped with two such bulbs, then what is the probability that it still illuminates a room after 1000 hours? Develop your answer by evaluating a double integral. What assumption must you make about the respective lifetimes of the bulbs?