Suppose that 62 %62% of families living in a certain country own aa minivanminivan and 16 %16% own aa trucktruck. The addition rule might suggest, then, that 78 %78% of families own either aa minivanminivan or aa trucktruck. What's wrong with that reasoning?

Events are not disjoint

Explanation:

Let A represents an event that 62% of families living in a certain country own a minivan and B represents an event that 16% own a truck.

As events A and B are not disjoint, so the addition rule does not imply that 78 %of families own either a minivan or a truck.

There may be some families who owe both minivans and trucks.