Suppose the probability that a person in a certan city will

Suppose the probability that a person in a certan city will contact a viral disease is .0095. If I randpmly selected 20 people in that city what is the probability that at least 1 of them will get the viral disease?

Solution

P(gettting disease) = 0.0095

P(not getting disease) = =0.9905

P(at least one) = 1 - P(none of them got the disease)

                      = 1- 20C₀ (0.9905)²⁰

                      => 1-0.8262 = 0.17379 (ans)