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Re: What is the probability that all 6 coins tossed together will turn up [#permalink]
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I think there's something wrong with the answer that's set.

Answer should be 1/16 = 1/2 x 1/2 x 1/2 x 1/2

We already know that two coins are heads so the probability for those two coins is irrelevant.

Answer is B.
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Re: What is the probability that all 6 coins tossed together will turn up [#permalink]
doomedcat wrote:
What is the probability that all 6 coins tossed together will turn up heads, if it is known that 2 of them have turned up Heads?

A) 1/4
B) 1/16
C) 1/64
D) 1/57
E) 7/57


Could you please share the explanation.
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Re: What is the probability that all 6 coins tossed together will turn up [#permalink]
1/57 is correct. One needs to apply Bayes theorem. The computation is

P(6H|2H) = P(2H|6H)P(6H)/(P(2H|6H)P(6H) + P(2H|5H)P(5H) + P(2H|4H)P(4H) + P(2H|3H)P(3H) + P(2H|2H)P(2H) + P(2H|1H)P(1H) + P(2H|0H)P(0H)) = 1/(1+6+15+20+15) = 1/57
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Re: What is the probability that all 6 coins tossed together will turn up [#permalink]
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Since we know the result of two tosses already. The possible combinations can be.
2H, 4T - 15 ways
3H, 3T - 20 ways
4H, 2T - 15 ways
5H, 1T - 6 ways
6H, 0T - 1 way

Fav. Events/Total events = 1/57

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Re: What is the probability that all 6 coins tossed together will turn up [#permalink]
Rongon04 wrote:
Since we know the result of two tosses already. The possible combinations can be.
2H, 4T - 15 ways
3H, 3T - 20 ways
4H, 2T - 15 ways
5H, 1T - 6 ways
6H, 0T - 1 way

Fav. Events/Total events = 1/57

Posted from my mobile device


Excellent explanation thanks 😊
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Re: What is the probability that all 6 coins tossed together will turn up [#permalink]
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