In Hawaii shark attacks are very rare. Furthermore, about 55% of all shark attacks are serious but not fatal (Reference: Sharks of Hawaii, Dr. Leighton Taylor, University of Hawaii Press). You are scheduled to give a talk at a local scuba club in Honolulu and want to include a brief statistical profile regarding the most recent 6 shark attacks, all of which were nonfatal. Let r be the number of nonfatal attacks out of a random sample of shark attacks.(Round your answers to three decimal places.)

a. What is the probability all six shark attacks are nonfatal?
b. What is the probability that 3 or more of the six shark attacks are nonfatal?
c. What is the expected number of nonfatal shark attacks out of the six?
d. What is the standard deviation of the -probability distribution?