Alaska has over half of al earthquakes in the United States. In particular, earthquakes with magnitude > 8 on the Richter scale occur in Alaska on average every 13 years. Suppose that these occur according to a Poisson process, and compute the probability that

1. A decade has no such earthquakes,
2. Two consecutive such earthquakes are at least 5 years apart,
3. A 13-year period has exactly one such earthquake,
4. Three consecutive decades have exactly one such earthquake each.