The neighborhood association sent a survey asking families to rank their concerns for the neighborhood. the four items listed were crime, recycling, speeding, and trash collection. in how many ways can a family answer this survey?

The life, in years, of a certain type of electrical switch has an exponential distribution with an average life b = 2. if 100 of these switches are installed in dif- ferent systems, what is the probability that at most 30 fail during the first year?