# What is the probability that at least 2 people have the same birthday in a group of 20 people?

Table of Contents

- 1 What is the probability that at least 2 people have the same birthday in a group of 20 people?
- 2 What is the probability that 2 persons have same birthday?
- 3 What is the rarest birthday?
- 4 Is April 13 a common birthday?
- 5 What is the probability of getting 53 Mondays in a leap year?
- 6 What is the least common birthday?
- 7 How do you find the probability that no two people share birthdays?
- 8 What is the meaning of various probability?

## What is the probability that at least 2 people have the same birthday in a group of 20 people?

0.411

Multiply that by the 0.9973 for two people and you have about 0.9918, the probability that three randomly selected people will have different birthdays….Probability of Shared Birthdays. or, How to Win Money in Bar Bets.

Probability in a group of n people that 2 or more have the same birthday | |
---|---|

20 | 0.411 |

22 | 0.476 |

23 | 0.507 |

## What is the probability that 2 persons have same birthday?

One person has a 1/365 chance of meeting someone with the same birthday. Two people have a 1/183 chance of meeting someone with the same birthday.

**What is the chance that at least two people were born on the same day of the week if there are 3 people in the room?**

Considering exactly 2 people being born on the same day I get 1*1/7*6/7. And then, exactly 3 people is 1*1/7*1/7. Thus, the total is 6/49 + 1/49 = 7/49.

**What is the probability of two friends having their birthday on the same day in a leap year?**

Probability of having same birthday = 1/365.

### What is the rarest birthday?

This Is the Least Common Birthday in the U.S. (No, It’s Not Leap Day)

- February 29.
- July 5.
- May 26.
- December 31.
- April 13.
- December 23.
- April 1.
- November 28.

### Is April 13 a common birthday?

You can see the full calendar year and how common of a birthday your special day is below….How common of a birth date is each day in the calendar year?

Birth Date | Popularity | Average Births |
---|---|---|

4/11 | 196th | 11,059 |

4/12 | 237th | 10,953 |

4/13 | 351st | 10,389 |

4/14 | 307th | 10,812 |

**How do you calculate the probability of the same birthday?**

The goal is to compute P(A), the probability that at least two people in the room have the same birthday. However, it is simpler to calculate P(A′), the probability that no two people in the room have the same birthday….Calculating the probability.

n | p(n) |
---|---|

350 | (100 − 3×10−129)% |

365 | (100 − 1.45×10−155)% |

≥ 366 | 100% |

**What is the probability of your friend being born in April?**

(365/365) * (1/365) = 1/365, or about 0.27%.

## What is the probability of getting 53 Mondays in a leap year?

In a leap year there will be 52 Mondays and 2 days will be left. Of these total 7 outcomes, the favourable outcomes are 2. Hence, the probability of getting 53 Mondays in a leap year P(E) = 2/7.

## What is the least common birthday?

Christmas Day

According to the chart, Christmas Day is the least common birthday, followed by New Years Day, and Christmas Eve and the 4th of July. There are also fewer birthdays on the 13th of each month, as compared to the 12th and 14th.

**Was there a day where no one was born?**

December 6th is a special day at Who2: it’s the only day of the year on which nobody in our database was born. That’s 2843 famous people (and counting) and none of them born on December 6th. The 6th has been the lone holdout for a couple of years now.

**What’s the rarest birthday date?**

The probability that no one shares the same birthday is the product of the probabilities that the second person doesn’t share their birthday with the first (D − 1) / D times the probability the third doesn’t share with the first two (D − 2) / D and so on down the line, until we get P (no common birthdays) = D − 1 D ⋯ D − n + 1 D.

### What is the meaning of various probability?

/ Various probability Calculates a table of the probability that one or more pairs in a group have the same birthday and draws the chart. n persons in a group (1) the probability that all birthdays of n persons are different.

**How many people have the same birthday?**

At least two people have the same birthday Ask Question Asked8 years, 4 months ago Active3 years, 8 months ago Viewed38k times 7 1 $\\begingroup$

**What is the probability of being born on February 29th?**

Leap years only happen every fourth year (more or less), so the probability that a person was born on February 29 is 1/1461 and the probability of every other day would be 4/1461.