the question goes as follows:
Medical case histories indicate that different illnesses may produce identical symptoms. Suppose that a particular set of symptoms, denoted , occurs only when one of the tress illnesses, occurs. Assume that the simultaneous occurrence of more ten one of these illnesses is impossible and that
in addition:
assuming that an ill person exhibits the symptoms, , what is the probability that the person has illness ?
solution:
To find
so
therefore:
is this correct, or am I missing something?