 # Odds of flipping heads 20 times in a row

The gambler's fallacyalso known as the Monte Carlo fallacy or the fallacy of the maturity of chancesis the erroneous belief that if a particular event occurs more frequently than normal during the past it is less likely to happen in the future or vice versawhen it has otherwise been established that the probability of such events does not depend on what has happened in the past.

Such events, having the quality of historical independence, are referred to as statistically independent. The fallacy is commonly associated with gamblingwhere it may be believed, for example, that the next dice roll is more than usually likely to be six because there have recently been less than the usual number of sixes.

The term "Monte Carlo fallacy" originates from the best known example of the phenomenon, which occurred in the Monte Carlo Casino in The gambler's fallacy can be illustrated by considering the repeated toss of a fair coin. In general, if A i is the event where toss i of a fair coin comes up heads, then:. If after tossing four heads in a row, the next coin toss also came up heads, it would complete a run of five successive heads. This is incorrect and is an example of the gambler's fallacy.

Since the first four tosses turn up heads, the probability that the next toss is a head is:. The reasoning that it is more likely that a fifth toss is more likely to be tails because the previous four tosses were heads, with a run of luck in the past influencing the odds in the future, forms the basis of the fallacy. If a fair coin is flipped 21 times, the probability of 21 heads is 1 in 2, Assuming a fair coin:. The probability of getting 20 heads then 1 tail, and the probability of getting 20 heads then another head are both 1 in 2, When flipping a fair coin 21 times, the outcome is equally likely to be 21 heads as 20 heads and then 1 tail. These two outcomes are equally as likely as any of the other combinations that can be obtained from 21 flips of a coin. All of the flip combinations will have probabilities equal to 0. Assuming that a change in the probability will occur as a result of the outcome of prior flips is incorrect because every outcome of a flip sequence is as likely as the other outcomes.

The fallacy leads to the incorrect notion that previous failures will create an increased probability of success on subsequent attempts. If a win is defined as rolling a 1, the probability of a 1 occurring at least once in 16 rolls is:. According to the fallacy, the player should have a higher chance of winning after one loss has occurred. The probability of at least one win is now:.If you're seeing this message, it means we're having trouble loading external resources on our website. To log in and use all the features of Khan Academy, please enable JavaScript in your browser. Donate Login Sign up Search for courses, skills, and videos. Math Precalculus Probability and combinatorics Compound probability of independent events using the multiplication rule.

### Coin Toss Probability Calculator

Compound probability of independent events. Probability without equally likely events. Independent events example: test taking. Die rolling probability with independent events. Coin flipping probability. Three-pointer vs free-throw probability.

Practice: Independent probability. Next lesson. Current timeTotal duration Google Classroom Facebook Twitter. Video transcript Now let's start to do some more interesting problems. And one of these things that you'll find in probability is that you can always do a more interesting problem. So now I'm going to think about-- I'm going to take a fair coin, and I'm going to flip it three times.

And I want to find the probability of at least one head out of the three flips. So the easiest way to think about this is how many equally likely possibilities there are. In the last video, we saw if we flip a coin 3 times, there's 8 possibilities.

For the first flip, there's 2 possibilities. Second flip, there's 2 possibilities. And in the third flip, there are 2 possibilities. So 2 times 2 times there are 8 equally likely possibilities if I'm flipping a coin 3 times.Thus, the probability of getting either five heads or five tails in five tosses is 1 in The probability of each coin flip, independently, is 0.

The probability of getting one result either heads or tails four times in a row is 0. Since two tails are independent events, the probability is 0. The probability of Tails on the first toss is 0. The probability of Tails on the second toss is 0. The probability of Tails on the third toss is 0. The probability of Tails on the fourth toss is 0. The probability of all four is 0. Assuming a fair coin, the odds of getting four tails in a row are 1 in The probability of getting a head first time is one out of two, or a half.

The probability of getting a head the next time is still one out of two, so the combined probability is one quarter. Similarly, one eighth is the probability of getting three in a row; but the pattern does not end there, the probability of getting a tails the next time is STILL one in two, so that is a one in sixteen chance of that run, the probability of the entire sequence is therefore one in thirty-two.

The answer I'm editing says the odds are 1 in 8. This is true only if you actually mean the probability of getting 3 tails in a row, rather than just 3 of either heads or tails in a row.

In mentioned case, the first flip doesn't matter which side it lands on, just the proceeding two flips do. The probability of rolling a six with a standard die five times in a row is 1 in 6 5 which equals 1 in or about 0. So the answer is one in eight, or Probability of girl, assumed to be 0.

Therefore, probability of 5 girls is 0. If you look at the as the probability of getting 1 or more tail in 4 coin tosses, you would then calculate the probability of tossing 4 heads in a row and subracting that from 1. In American roulette there are 18 black pockets on the wheel, 18 red pockets, a "0" pocket and a "00" pocket. So there are 38 pockets in total. The probability of getting five blacks in a row is therefore 0.

The odds ratio of probable success to failure of getting five blacks is therefore The probability of several independent events happening together is the product of their individual probabilities. Asked By Curt Eichmann. Asked By Leland Grant. Asked By Veronica Wilkinson.

Asked By Daija Kreiger. Asked By Danika Abbott. Asked By Consuelo Hauck. Asked By Roslyn Walter. All Rights Reserved. The material on this site can not be reproduced, distributed, transmitted, cached or otherwise used, except with prior written permission of Multiply. Ask Login. Asked by Wiki User. Top Answer. Wiki User Answered If you are puting it in a ratio format, the answer would be If you flip a coin 10 times, what are the odds of it landing on Heads or Tails for that matter ALL 10 times?

The second part makes no sense at all. Do you mean you need to toss 9 sequenses of 9 heads in a row? Either way you need to make sure you understand the problem before you ask someone else for help. But if you want it to land on heads nine consecutive times than it would be. Hope that helps. Trending News. A warning sign for Trump at The Villages in Florida. Lucille Ball's great-granddaughter dies at Virginia health officials warn of venomous caterpillars. NBA star Kevin Love's honest talk about mental health.

Scientists debunk Pence debate claim on hurricanes. Miami Heat spoiled LeBron's potential masterpiece. Video of ICE agents stopping Black jogger. Experts blast Trump for foreign policy blunders. Popular beer brand jumps on trendy bandwagon. Answer Save. How do you think about the answers?

You can sign in to vote the answer. David L. Still have questions? Get your answers by asking now.Some people think "it is overdue for a Tail", but really truly the next toss of the coin is totally independent of any previous tosses. Saying "a Tail is due", or "just one more go, my luck is due to change" is called The Gambler's Fallacy.

Probability goes from 0 imposssible to 1 certain :. We can calculate the chances of two or more independent events by multiplying the chances.

Question 2: When we have just got 6 heads in a row, what is the probability that the next toss is also a head? You can have a play with the Quincunx to see how lots of independent effects can still have a pattern. Time: you want the 2 hours of "4 to 6", out of the 8 hours of 4 to midnight :.

Both methods work here. But you were probably sharing an experience movie, journey, whatever and so your thoughts were similar. Hide Ads About Ads. Probability: Independent Events Life is full of random events!

You need to get a "feel" for them to be a smart and successful person. The toss of a coin, throwing dice and lottery draws are all examples of random events. There can be: Dependent Events where what happens depends on what happened before, such as taking cards from a deck makes less cards each time learn more at Conditional Probabilityor.

Example: You toss a coin and it comes up "Heads" three times What it did in the past will not affect the current toss! Example: what is the probability of getting a "Head" when tossing a coin?

Example: what is the probability of getting a "4" or "6" when rolling a die? Example: the probability of getting a "Head" when tossing a coin: As a decimal: 0. Because we are asking two different questions: Question 1: What is the probability of 7 heads in a row? Example: your boss to be fair randomly assigns everyone an extra 2 hours work on weekend evenings between 4 and midnight.

### What are the odds of a coin landing on heads nine times in a row?

What are the chances you get Saturday between 4 and 6? Example: the chance of a flight being delayed is 0. Result: 0. Example: you are in a room with 30 people, and find that Zach and Anna celebrate their birthday on the same day.

Do you say: "Wow, how strange! Why is the chance so high? Because you are comparing everyone to everyone else not just one to many.

Example: Snap! Did you ever say something at exactly the same time as someone else?

Benford's Law - How mathematics can detect fraud!

Wow, how amazing! And there are only so many ways of saying something So, maybe not so amazing, just simple chance at work. Probability Data Index.If you are puting it in a ratio format, the answer would be If you flip a coin 10 times, what are the odds of it landing on Heads or Tails for that matter ALL 10 times?

The second part makes no sense at all. Do you mean you need to toss 9 sequenses of 9 heads in a row? Either way you need to make sure you understand the problem before you ask someone else for help.

But if you want it to land on heads nine consecutive times than it would be. Hope that helps. Trending News. A warning sign for Trump at The Villages in Florida. Lucille Ball's great-granddaughter dies at Virginia health officials warn of venomous caterpillars. NBA star Kevin Love's honest talk about mental health.

Scientists debunk Pence debate claim on hurricanes. Miami Heat spoiled LeBron's potential masterpiece. Video of ICE agents stopping Black jogger. Experts blast Trump for foreign policy blunders. Popular beer brand jumps on trendy bandwagon. Rejected: Trump campaign access to Philly voter offices.

Answer Save. How do you think about the answers? You can sign in to vote the answer. David L. Still have questions?Understanding probability. Formula for percentage. Finding the average. Basic math formulas Algebra word problems. Types of angles. Area of irregular shapes Math problem solver. Math skills assessment. Compatible numbers. Surface area of a cube.

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## Probability: Independent Events

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