1. G

    Birthday problem

    Please, help me ) 1. Find the probability that in a group of five people no more than two people are born on the same day of the week. 2. Find the probability that in a group of five people exactly three people are born on the same day of the week. 3. Find the probability that in a group of 32...
  2. R

    Birthday Math Question

    No one has been able to solve this 5th grade math question. Can someone solve it step by step?
  3. C

    Birthday Probability

    Hi guys, I have a question that I was talking about with someone a little while ago. The question is as follows: If you have 4 people, what is the chances that 2 of them share the same birthday as well as the other 2 sharing a different birthday. Example: 1st Jan, 1st Jan, 3rd May, 3rd May...
  4. sfspitfire23

    Birthday paradox-probabiliy

    Hey guys- 25 people line up. What is the probability that there will be two people with the same birth month standing next to each other in the line?
  5. K

    The Birthday Problem...With an Added Evil Bonus

    Summary: I'm horrible with math. Anyone willing to help me out here? (Note, this problem is derived from a comment made in a meeting at work. This is not a homework assignment.) I want to calculate the probability that two people in a room of 18 people have the same birthday in the same...
  6. G

    Please verify: a twist on the Birthday Problem

    Hello, I was assigned some optional practice on the birthday question. I got all the questions on the birthday problem itself correct, but although I got an answer for this last one (n >= 612.257), it seems VERY unintuitive to me. Can you please confirm whether it's right or what I did wrong...
  7. P

    Generalised Birthday Paradox - bins problem

    We are putting balls into bins by the Uniform Distribution. Let X be a Random Variable and means moment of collision when two balls fall into the same bin. So minimum X is 2 (2 balls in the same bin) and maximum X is n+1. What is probability P(2 \le X \le n+1) and Expected Value for k bins...
  8. M

    birthday favors

    We all know welly birthday is a very beautiful and enjoyable moment for our life. birthday favors Birthday comes every year of our life. We can not mistake our birthday.
  9. M

    Birthday Presents

    Thinking of birthday presents every year is indeed a daunting task! The following article will provide you with some unique birthday present ideas which are sure to bring a wide smile on the birthday star's face!Buying a gift for loved ones is really exciting, and if it is for their birthday, it...
  10. M

    Good Birthday Presents

    Birthdays are perhaps the most important days of our lives. As we get older, it epitomizes a new beginning. They are great fun with presents, goodies and all the good food. A few gifting options for this special day are given below.It is a special day for your near and dear ones and you should...
  11. S

    HELP! Assignment Question, Probability of Two people having the same birthday

    The Question is as follows: Statisticians are prone to trying to impress their friends with random facts that may not be mathematically intuitive. One such fact that is repeated ad nauseum relates to the probability of people sharing a birthday. The common claim is that the probability of at...
  12. B

    Birthday Problem; Prime Number Problem

    I am currently teaching myself some maths but I have found these two questions on the internet, and I'm completely stuck. The questions are: 1.A man whose birthday was January 1st died on Feb 9th 1992. He was x years of age in the year x^2 AD for some interger x. In what year was he born? 2...
  13. M

    Variation on the birthday problem

    Hi All, Suppose a randomly selected group of \textit{k} people are brought together. What is the probability that exactly one pair has the same birthday? The solution is {k\choose{2}} \cdot \left( 365 \cdot 364 \cdots(365-k+2) \over 365^k \right) But I'm can't see exactly why this is so. Any...
  14. D

    Question on the Birthday Problem

    Hello all! I had a quick question on the (in)famous birthday problem, The question itself reads : Assuming that people are equally likely to be born in each of the twelve months, how many people must be gathered to guarantee a probability of at least 0.5 that two of them have birthdays in...
  15. M

    30 people, 365 days, birthday

    There is 30 people in a group (29 + you). What's the probabillity that one of them has the exact same birthday as you? This is what I've got thus far. I have no idea how to check if it's correct though. 30 * (1/365)^1 * (364/365)^29 = 0.076 = 7.6%
  16. M

    birthday problem

    Given 20 people, what is the probability that among the 12 months in the year there are 4 months containing exactly 2 birthdays and 4 containing exactly three birthdays. I'm able to proceed as far as computing the sample space which is 12^20, but no further. Can some one shed some light on...
  17. M

    birthday paradox

    hello everyone this problem is in cryptography but it's a pure Probability problem. if we have a text of "M" length and we randomly pick 3 number between 1 and M. we observe the letters in those places. what is the Probability that we will have two identical letters? i thought i could...
  18. S

    estimate through trials P(n people sharing birthday) given r people in a room

    Hi, There are extensive resources on the internet and in this forum discussing the famous birthday paradox. It is clear to me how to calculate the probability of two people sharing a birthday i.e. P(s)=1-P(d). However i can't find any hints when it comes to estimating a probability without...
  19. A

    Probability that celebrities are less likely to die in the month of their birthday

    I am not sure whether I have approached this question correctly... I would appreciate your input on my answer and any suggestions regarding any other calculations I should be doing. Thanks in advance. Question: Evidence has been produced that famous people are less likely to die in the...
  20. G

    Birthday Spacing test

    Hi, Could someone please help me to understand the Birthday Spacing test? Suppose that I have one sample (1,3,9,40,20,50,..., 91), say, and I want to use it for testing the random number generator (that takes value on (0,99), for example). How can it be done using the Birthday Spacing test...