hey folks,(adsbygoogle = window.adsbygoogle || []).push({});

My question is how to find probability of getting 3 CONSECUTIVE heads or more in 20 coin flips, what are the odds

I have an approach which I need to verify and please clarify in case of missing points.

No. of possible outcomes = 2 ^ 20

first I assume that first 3 outcomes are heads , all other 17 combinations of coins are to be counted, so there are 2 ^ 17 .

then I assume first outcome is tail, and 2nd,3rd,4th outcomes are heads, all other 16 combinations of coins are to be counted , so there are 2^16

then I assume first outcome AND second outcome both are tail, and 3rd,4th,5th outcomes are heads , other 15 combinations are 2^15

then I assume first outcome , second outcome AND third outcome all are tail, and 4th,5th,6th outcomes are heads , other 14 combinations are 2^14

and so on until

1st to 17th outcome are all tail , and 18th,19th,20th are heads, possibility is 2^0 which is 1

so the answer is 2^17 + 2^16 + 2^15 + ...... 2^0 which gives 262143 , with a probability of 0.25

are there any misleading overlapping cases?

and please check R software or matlab or others to get the exact answer

**Physics Forums - The Fusion of Science and Community**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# I Probability of getting 3 heads or more in 20 coin flips

Tags:

Have something to add?

Draft saved
Draft deleted

Loading...

Similar Threads - Probability getting heads | Date |
---|---|

B Cant get Venn diagram to agree with Demorgan's Law | Oct 10, 2016 |

Probability of getting three heads in five tosses of two coins? | Apr 17, 2013 |

Elementary probability problem I can't get my head round! Help! | Jun 20, 2011 |

How to get probability from a normal distribution? | Nov 25, 2010 |

What is the probability of getting 15 or more CONSECUTIVE heads over 40 coin tosses? | Aug 19, 2009 |

**Physics Forums - The Fusion of Science and Community**