# Classical Probability Approach

The definition of classical probability is

Classical Probability: If a random experiment can result in $n$ mutually exclusive and equally likely outcomes and if $n_A$ of these outcomes have an attribute $A$, then the probability of $A$ is the fraction $n_A/n.$

In the book Mood, A. M., Graybill, F. A., & Boes, D. C. (1974). Introduction to the Theory of Statistics 1974. McGraw-Hill Kogakusha, it is written that

difficulty with the classical approach is encounterd when we try to answer the question: What is the probability that a child born in Chicago will be a boy?

Why can't classical definition answer it? Isn't it simply $0.5$, as the child's being a male or female is equally likely?

• The first quotation isn't a definition at all: it's a formula for a model. Should you choose to apply it, your first duty is to demonstrate that it is at least approximately correct--and that puts you right back to the beginning: what is "probability" in the first place and how do you measure it?
– whuber
Jun 18 '18 at 13:29