The table lists the number of U.S. mainland hurricane strikes (from 1851 to 2008) for various intensities according to the Saffir-Simpson Hurricane Scale. (Source: National Oceanic and Atmospheric Administration)

(a) Construct a probability distribution of the data.

(b) Graph the discrete probability distribution using a probability histogram. Then describe its shape.

(c) Find the mean, variance, and standard deviation of the probability distribution and interpret the results.

(d) Find the probability that a hurricane selected at random for further study has an intensity of at least four.