In a school outbreak of food poisoning, 100 students ate a chicken sandwich, and 60 of them developed symptoms. 50 students did not eat the chicken sandwich, and 10 of them developed symptoms. What is the *attack rate* among those who ate the chicken sandwich?

Explanation

The attack rate among those who ate the chicken sandwich is calculated as the number of people who became ill after eating the chicken sandwich divided by the total number of people who ate the chicken sandwich, expressed as a percentage. In this case, (60 ill / 100 exposed) * 100% = 60%.