At an elementary school, 4% of children are allergic to peanut butter. To celebrate Kathy's birthday, a teacher decided

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At an elementary school, 4% of children are allergic to peanut
butter. To celebrate Kathy's birthday, a teacher decided to bring
peanut butter sandwiches for all the children. When the teacher
looks at Bobby though, she realizes Bobby didn't grab a peanut
butter sandwich. Among students who are not allergic to peanut
butter, 80% will eat peanut butter sandwiches whenever they get a
chance. By contrast, no student who is allergic will eat peanut
butter sandwiches. Based on the evidence, what is the probability
that Bobby is allergic to peanut butter, expressed as a percentage
rounded to the nearest integer? (Your answer should be a number
between 0 and 100 with no percentage sign.)?