Respuesta :

1. the total of an area under the curve must be equal to one. 2. Every point of the curve must have an vertical height that is 0 or greater.

Step-by-step explanation:

1. The area under the curve adds up to 1.0, because the sum of probabilities in all situations/events is 1.0.

2. The domain is (-infinity, +infinity).  The impossible events are given a probability of zero, if applicable.