A study conducted by a research group in a recent year reported that

58% of cell phone owners used their phones inside a store for guidance on purchasing decisions. A sample of 13 cell phone owners is studied. Round the answers to four decimal places.

(a) What is the probability that seven or more of them used their phones for guidance on purchasing decisions?

(b) What is the probability that fewer than ten of them used their phones for guidance on purchasing decisions?

(c) What is the probability that exactly eight of them used their phones for guidance on purchasing decisions?

(d) Would it be unusual if more than 10 of them used their phones for guidance on purchasing decisions? What is the probability of more than 10 people using their phones?