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Card probability uses the Hypergeometric Distribution to calculate the probability of drawing specific cards from a standard 52-card deck without replacement. Unlike dice (with replacement), each card drawn changes the composition of the deck, making the probabilities hypergeometric rather than binomial.

Формула

N = deck size (52), K = cards of target type, n = hand size, k = desired count
N
n! / (k! × (n−k)!) — combinations formula — n! / (k! × (n−k)!) — combinations formula
K
sum of P(X=k) + P(X=k+1) + — sum of P(X=k) + P(X=k+1) +
n
n! / (k! × (n−k)!) — combinations formula — n! / (k! × (n−k)!) — combinations formula
k
sum of P(X=k) + P(X=k+1) + — sum of P(X=k) + P(X=k+1) +

Водич корак по корак

  1. 1Hypergeometric: P(X=k) = C(K,k) × C(N−K, n−k) / C(N,n)
  2. 2N = deck size (52), K = cards of target type, n = hand size, k = desired count
  3. 3C(n,k) = n! / (k! × (n−k)!) — combinations formula
  4. 4P(at least k) = sum of P(X=k) + P(X=k+1) + ... + P(X=K)

Worked Examples

Инпут
5-card hand, probability of exactly 1 ace (K=4, n=5, k=1)
Резултат
≈ 34.12%
C(4,1)×C(48,4)/C(52,5)
Инпут
5-card hand, at least 1 ace
Резултат
≈ 34.12% + 21.37% + ... ≈ 34.12% (exactly 1) + others
Инпут
7-card hand (Texas Hold'em + 2 in pocket), 2 aces
Резултат
≈ 6.79% of starting hands are pocket aces

Frequently Asked Questions

What is Card Probability?

Card probability uses the Hypergeometric Distribution to calculate the probability of drawing specific cards from a standard 52-card deck without replacement. Unlike dice (with replacement), each card drawn changes the composition of the deck, making the probabilities hypergeometric rather than binomial

How accurate is the Card Probability calculator?

The calculator uses the standard published formula for card probability. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

What units does the Card Probability calculator use?

This calculator works with inches. You can enter values in the units shown — the calculator handles all conversions internally.

What formula does the Card Probability calculator use?

The core formula is: Hypergeometric: P(X=k) = C(K,k) × C(N−K, n−k) / C(N,n). Each step in the calculation is shown so you can verify the result manually.

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