Whooping cough (pertussis) is a highly contagious bacterial infection that was a major cuase of childhood deaths before the development of vaccines. About80%

80

%

of unvaccinated children who are exposed to whooping cough will develop the infection, as opposed to only about5%

5

%

of vaccinated children.

A group of 4 vaccinated children at a nursery school are exposed to whooping cough by playing with an infected child. What is the probability that at least one of the 4 children develop an infection?