I drew a hand that contains the Sun and the Moon from a tarot deck with $78$ cards. I want to find the probability of this occurring. I think because there are $78 \choose 6$ distinct arrangements of the $6$ other cards in the hand, and $78\choose8$ distinct hands, the probability of choosing both the Sun and the Moon is $$\frac{78 \choose 6}{78 \choose 8}=1/9.$$ But $1/9$ seems pretty high. Am I missing something?
2026-03-30 06:49:59.1774853399
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What is the probability of pulling 2 specific cards in a hand of 8 from 78 cards?
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Simulation (to check):
deck = c(1,1,rep(0,76))
table(deck)
deck
0 1
76 2
set.seed(406)
sm = replicate(10^6, sum(sample(deck,8)))
mean(sm==2)
[1] 0.009219 # aprx 0.0093
sd(sm==2)/1000
[1] 9.557206e-05 # 95% marg of sim err
Simulated value is $0.0092 \pm 0.0001.$
choose(76, 6)/choose(78,8)
[1] 0.009324009
It would be
$$\frac{1\cdot{76\choose 6}}{{78\choose 8}}\approx0.009324009$$
where you can replace $1$ with ${2\choose 2}$