Two cards are drawn **without replacement** from a standard $52$-card deck. What is the probability that **both** cards are aces?
A$\dfrac{1}{169}$
B$\dfrac{1}{221}$
C$\dfrac{1}{2{,}652}$
D$\dfrac{4}{169}$
Answer & Solution
Correct answer: B. $\dfrac{1}{221}$
First card ace: $P_{1} = \dfrac{4}{52} = \dfrac{1}{13}$.
Given the first was an ace, only $3$ aces remain in $51$ cards: $P_{2 \mid 1} = \dfrac{3}{51} = \dfrac{1}{17}$.
Combined: $P = \dfrac{1}{13} \cdot \dfrac{1}{17} = \dfrac{1}{221}$.
- Trap A ($1/169 = (4/52)^2$) assumes replacement (independence).
- Trap C is a wrong numerator.
- Trap D divides wrong.
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