Common causes of anaphylaxis include medication, peanuts, tree nuts, insect stings, fish, shellfish, and milk. Exposure to tree nuts is found to be the cause of anaphylactic shock in 17% of the cases among school children. Concerned about the severe consequences of an anaphylactic shock, a public health manager investigates 5 students with anaphylactic shock that occurred over the last year.

What is the probability that of these 5 students, at least 4 students had an anaphylactic shock because of exposure to tree nuts? Would it be unusual for a public health manager to find at least 4 cases of anaphylactic shock due to exposure to tree nuts?