1. The problem statement, all variables and given/known data a) A lamp has two bulbs of a type with an average lifetime of 1000 hours. Assuming that we can modelthe probability of failure of these bulbs by an exponential density function [tex]\mu[/tex] = 1000, find the probability that both of the lamps bulbs will fail within 100 hours. b) Another lamp has just one bulb of the same type as in part (a). if one bulb burns out and is replaced by a bulb of the same time, find the probability that the two bulbs fail within a total of 1000 hours. 2. Relevant equations 3. The attempt at a solution I'm pretty sure [tex]\mu[/tex] = double integral on a region D of xf(x,y)dA but I don't know what my region or f(x,y) would be.