Posterior Probability of a Double-Headed Coin

Probability · Easy · Free problem
A jar contains 12 coins: 10 are fair (equal chance of heads or tails), and 2 are double-headed (always land heads). You pick a coin uniformly at random from the jar and flip it 5 times. All 5 flips come up heads. What is the posterior probability that the coin you picked is double-headed?

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