When A is an impossible event, then what is P(A)?

Answer

To solve the question, we need to understand the concept of probability, particularly in relation to impossible events.

### Step-by-Step Solution:

1. **Definition of an Impossible Event**:
An impossible event is an event that cannot occur under any circumstances. For example, rolling a 7 on a standard six-sided die is an impossible event.

2. **Understanding Probability**:
Probability is a measure of how likely an event is to occur, and it is expressed as a number between 0 and 1. A probability of 0 means the event cannot happen, while a probability of 1 means the event will definitely happen.

3. **Assigning Probability to Impossible Events**:
Since an impossible event cannot occur, the probability of such an event happening is defined as 0.

4. **Conclusion**:
Therefore, if A is an impossible event, we can conclude that:
\[ P(A) = 0 \]

### Final Answer:
When A is an impossible event, then \( P(A) = 0 \).

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