a radioactive mass emits particles according to a poisson process at a mean rate of 3 per second. let t be the waiting time, in seconds, between emits. a. what is the probability that between 1 and 5 seconds elapses between emits? b. assume that the times between emissions of particles by the radioactive mass are independent. 10 times between emissions are randomly selected. what is the probability that exactly 2 of the times between emissions are between 1 and 5 seconds?