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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.

Formula

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) +

Guida passo passo

  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)

Esempi risolti

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

Domande frequenti

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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