1. **State the problem:** We need to find the conditional probability that a card drawn from a standard 52-card deck is black, given that it is a spade. 2. **Recall the formula for conditional probability:** $$P(A|B) = \frac{P(A \cap B)}{P(B)}$$ where $A$ is the event "card is black" and $B$ is the event "card is a spade". 3. **Identify the events:** - Event $A$: card is black (clubs or spades). - Event $B$: card is a spade. 4. **Find $P(B)$:** There are 13 spades in a 52-card deck, so $$P(B) = \frac{13}{52} = \frac{1}{4}$$ 5. **Find $P(A \cap B)$:** The card is black and a spade means the card is a spade (since all spades are black). So, $$P(A \cap B) = P(B) = \frac{13}{52} = \frac{1}{4}$$ 6. **Calculate the conditional probability:** $$P(A|B) = \frac{P(A \cap B)}{P(B)} = \frac{\frac{1}{4}}{\frac{1}{4}} = 1$$ 7. **Interpretation:** Given that the card is a spade, the probability it is black is 1 because all spades are black cards. **Final answer:** $$\boxed{1}$$