13. Probability
I'm going to flip a coin four times.
The first time the coin shows heads.
The second time, the coin shows heads again.
And so does the third time.
What are the odds that flipping the coin a fourth time will show tails?
Submitted by xfx · Added 10 May 2008
Solution:
The odds of flipping tails on the fourth coin flip are still 50%, regardless of the previous results. Each coin flip is an independent event, meaning that previous outcomes do not affect the probability of future outcomes.
Comments (14)
Three consecutive heads is not enough to judge as to the fairness of the coin, so we'll assume that it is a fair coin (if you had flipped 100 consecutive heads, then you could certainly assume that it is not a fair coin).
That given, the probability of a tail is 1/2, or 50%. If you really want odds, then the odds of a tail is 1:1 , which is P(tail) / P(head)
1/2 50% Half. It only relies on the prob of landing on side 1 or side 2, it dosnt matter the past flips. Its based on luck.
That's absolutely correct Hahaveryfunny:3
The answer would appear to be 15/16, because the chances of it being heads again is 1/16, but its actually 1/2 because the probability of one side does not affect the probability of the other.
Hahaveryfunny:3 had it right -- every other answer/assumption is wrong
50/50 of course
50/50, doesn't matter what happened on the last three goes
as it is not mentioned its a non biased coin
yellow, because ice cream doesn't have any bones.
This, I do not know. The odds on a standard coin would be near 1:1 leaning in favor of heads for slightly less gravity and there is also the VERY slim chance that the coin lands on its side. (I'd like to see that happen.)
But there is still the possibility that the coin is a double-header.
The probabilty is 100%. It's the same as throwing a knife. If you grab it by the handle it will hit with the handle. This is also the reason why in a coin game you aren't allowed to see the coin before betting.
it's 50/50 or 50%. both sides are possible until the coin lands.
just because the coin was landing on heads each time before that, it doesn't mean anything.
UNLESS
if this coin is weighted, then the chance of it landing on tails is 0%.
The coin has demonstrated a propensity to show heads. Therefore I believe answer to the question is the odds of tails on the fourth flip is strictly less than 50%. But after only 3 flips its damn near 50%.
50 percent
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