We have this formula:1) The secretary of a college has calculated that from the students
who took calculus, physics and chemistry last semester:
78% passed calculus
80% passed physics
84% passed chemistry
60% passed calculus and physics
65% passed physics and chemistry
70% passed calculus and chemistry, and
55% passed all three.
Show that these numbers are not consistent,
and therefore the secretary has made a mistake
Then we have:
The data adds up to more than 100% . . . clearly impossible.