5 card poker hand contains 3 aces, conditional probability question

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Really struggling with this question and could use some guidance.

If a poker hand (five cards) is known to contain at least three aces, what is the probability that it contains all four aces?

I have been taking an approach using conditional probability to solve this and am coming up short. Thanks in advance

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If there are at least three aces in the hand, either it contains exactly three aces or exactly four aces. Thus $$P(4A|\ge3A)=\frac{P(4A)}{P(3A)+P(4A)}=\frac{\#(4A)}{\#(3A)+\#(4A)}=\frac{48}{\binom43\binom{48}2+48}=\frac{48}{4560}=\frac1{95}$$ where $\binom43\binom{48}2$ consists of choosing three aces from four and two cards from the 48 non-aces.