Question

The school nurse took care of five students on Monday and four of the five students had a cough. The school nurse determined that 80% of the students in her school were coming down with colds. Which of the following would best describe why her conclusion was invalid?

Answer 1

It is not valid because she only saw 5 students and that's not a large enough sample for the whole school.

Explanation:

While 4/5 IS 80%, the nurse assumed that 80% of ALL of the students in the school were coming down with colds. This is not true since only 4 students had colds. If she were specific and said that 4/5 students who visited her on Monday were 80% coming down with colds, she'd be right. But she isn't since she's assuming it's 80% of the whole school's population of students.