Birthday Recipes Food Cooking International Guide
Birthday By Numbers
By Jane Kliperrs
There is a birthday paradox, or, as it is sometimes called, the
birthday coincidence. This happens when two people, within a small
group, celebrate the same birth day. Some people find it surprising
that only a small group of people is actually needed to have the
fifty/fifty probability of having a matching date of birth.
To show how to calculate the probability of a group finding such
a match, before setting off to find the perfect birthday present,
it is simpler to first find the probability of all the birthdays
being different. Consider a group of two people. The first person
could have been born on any of the 365 days of the year, while
the second must have been born on one of the other 364 days in
order to not match.
Probability Of The Same Date Of Birth
The first person has a probability of 365/365, which equals 1.0,
and the second has a probability of 364/365 which is 0.9973. Multiplying
these probabilities together gives a net probability of 0.9973
for having different birthdays. Subtracting this number from 1.0
gives a 0.0027 probability of having the same date of birth.
When you start adding more people to the group the odds naturally
change. For example, a third person added has to miss having the
same birthday as the first two and has only 363 days in which
to do so and that changes the probability to 0.9945, or 363/365,
and multiplying it to your previous results gives you a 0.9918
chance of them having the same birth day. And, of course, it changes
again when you add a fourth person to the equation, 1 - 0.9836=
0.0164 which is over 1%.
Adding More People To The Group
As you add more and more people to the group, the number of non-matching
days available continues to decrease; and the probability of everyone
celebrating a different birth day decreases.
The probability of there being two children born on the same
day increases and continues to multiply more and more, smaller
and smaller fractions, a point near 0.5 is exceeded as soon as
the group consists of 23 people. And, once you have 80 people
in the group, only one time in ten thousand will everyone celebrate
different birthdays.
The Sentiment Of A Special Day
Of course not everyone is interested in taking a sentimental
subject such as this and applying analytical thoughts and processes
to it; preferring to leave all of the percentages, probabilities,
equations and statistics to those who truly enjoy that sort of
thing.
Most people prefer to think of a birthday in a special way, which
includes celebrating with a birthday cake, presents and birthday
cards. Most often, except in the case of multiple births, this
sentiment is applied to one special person on their own special
day honoring them alone and not with anyone else who may share
the same date of birth.
About the Author:
By Jane Kliperrs has written a number of articles on food and
party ideas including Birthday
Party Supplies, The
Birthday Party, Party
Supplies, Party
Supply Tips, Party
Supply Store, Party
Supply Store, Birthday
Party Rental, Gift
Ideas Unique, Mothers
Day Gift, Wedding
Gift Ideas, Unique
Gift.
Keep a lookout for more articles on this website.
Facts About Birthday Ideas
Let’s face the facts. Even grown-ups like birthday parties. It
may not be all about cake and ice cream but it is still a celebrated
event to look forward to each year. You get another year older
and hopefully a little bit wiser. If you are in charge of planning
a festive event for a friend or loved one, it can be hard to come
up with good ideas. Lucky for you there are plenty of resources
to turn to that can help you have the best party you possibly
can.
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