Ared light bulb has been flashing forever, according to a poisson process with rate r . similarly, a blue bulb has been flashing forever, , according to an independent poisson process with rate b . let us fix t to be 12 o'clock. what is the expected length of the interval that t belongs to? that is, find the expected length of the interval from the last event before t until the first event after t . here, an event refers to either bulb flashing.