A standard deck of playing cards has 52 cards in total. Here's how we calculate the probability that the card drawn is an ace or a red card:

1. Total number of cards in the deck: 52
2. Number of aces: 4
3. Number of red cards (hearts and diamonds): 26
4. Overlap (red aces): 2 (ace of hearts and ace of diamonds)

Using the principle of inclusion and exclusion for probabilities:

$P(\text{Ace or Red Card}) = P(\text{Ace}) + P(\text{Red Card}) - P(\text{Red Ace})$

$P(\text{Ace or Red Card}) = \frac{4}{52} + \frac{26}{52} - \frac{2}{52}$

Simplify the numerator:

$P(\text{Ace or Red Card}) = \frac{4 + 26 - 2}{52} = \frac{28}{52}$

Reduce the fraction:

$P(\text{Ace or Red Card}) = \frac{7}{13}$

Final Answer:

$\boxed{\frac{7}{13}}$

Would you like a breakdown of this solution or further clarification?

Here are five follow-up questions to deepen understanding:

1. What is the probability of drawing a face card from a standard deck?
2. How do we calculate probabilities when two events are mutually exclusive?
3. How many black cards are there in a standard deck, and what is the probability of drawing one?
4. What is the probability of drawing a heart from a standard deck?
5. How would the calculation change if jokers were included in the deck?

Tip: Always check for overlaps (intersection) when calculating probabilities of "or" events to avoid double counting!