Home |
Search |
Today's Posts |
#1
Posted to microsoft.public.excel.misc
|
|||
|
|||
Birthday probability
Hi,
I can work out the probabilities for 2 people in the same room sharing a birthday by dragging formula down like so No People Different Same % 2 364 365 99.73% 0.274% 3 363 365 99.18% 0.820% 4 362 365 98.36% 1.636% But can anyone get this equation into a single formula where I imput n for the number of people in the room and the probability is calculated. And secodly a formula for the probability as the same birthday as me Dave |
#2
Posted to microsoft.public.excel.misc
|
|||
|
|||
Birthday probability
From Daytona Beach:
http://go.dbc.edu/mathematics/walsh_...3E5943B498.pdf -- Gary''s Student - gsnu200766 "Dave" wrote: Hi, I can work out the probabilities for 2 people in the same room sharing a birthday by dragging formula down like so No People Different Same % 2 364 365 99.73% 0.274% 3 363 365 99.18% 0.820% 4 362 365 98.36% 1.636% But can anyone get this equation into a single formula where I imput n for the number of people in the room and the probability is calculated. And secodly a formula for the probability as the same birthday as me Dave |
#3
Posted to microsoft.public.excel.misc
|
|||
|
|||
Birthday probability
Your data seems wrong. It is generally accepted that about 23 people give a 50% chance of 'clash' And after 100 it is essential 100% Have a look at: http://en.wikipedia.org/wiki/Birthday_paradox Do not try to compute 365! (in Excel FACT(365)) -- Bernard V Liengme Microsoft Excel MVP www.stfx.ca/people/bliengme remove caps from email "Dave" wrote in message ... Hi, I can work out the probabilities for 2 people in the same room sharing a birthday by dragging formula down like so No People Different Same % 2 364 365 99.73% 0.274% 3 363 365 99.18% 0.820% 4 362 365 98.36% 1.636% But can anyone get this equation into a single formula where I imput n for the number of people in the room and the probability is calculated. And secodly a formula for the probability as the same birthday as me Dave |
#4
Posted to microsoft.public.excel.misc
|
|||
|
|||
Birthday probability
Hi,
I'm confused, why do you say my data are incorrect? If I drag my formula down then for 23 people I get a 50.73% chance that 2 people share the same birthday and a 49.27% chance they don't 21 345 365 55.63% 44.369% 22 344 365 52.43% 47.570% 23 343 365 49.27% 50.730% 24 342 365 46.17% 53.834% 25 341 365 43.13% 56.870% The formula in Column D dragged down is D2 = =B2/C2 D3 = =B3/C3*D2 This is the dragged formula Mike "Bernard Liengme" wrote: Your data seems wrong. It is generally accepted that about 23 people give a 50% chance of 'clash' And after 100 it is essential 100% Have a look at: http://en.wikipedia.org/wiki/Birthday_paradox Do not try to compute 365! (in Excel FACT(365)) -- Bernard V Liengme Microsoft Excel MVP www.stfx.ca/people/bliengme remove caps from email "Dave" wrote in message ... Hi, I can work out the probabilities for 2 people in the same room sharing a birthday by dragging formula down like so No People Different Same % 2 364 365 99.73% 0.274% 3 363 365 99.18% 0.820% 4 362 365 98.36% 1.636% But can anyone get this equation into a single formula where I imput n for the number of people in the room and the probability is calculated. And secodly a formula for the probability as the same birthday as me Dave |
#5
Posted to microsoft.public.excel.misc
|
|||
|
|||
Birthday probability
Hi,
Thank you for that but it really is only a repeat of what I have done,what I really wanted; and it might not be dooable, is a formula in a single cell that works out the probability for n where n is the number of people in the room. D "Gary''s Student" wrote: From Daytona Beach: http://go.dbc.edu/mathematics/walsh_...3E5943B498.pdf -- Gary''s Student - gsnu200766 "Dave" wrote: Hi, I can work out the probabilities for 2 people in the same room sharing a birthday by dragging formula down like so No People Different Same % 2 364 365 99.73% 0.274% 3 363 365 99.18% 0.820% 4 362 365 98.36% 1.636% But can anyone get this equation into a single formula where I imput n for the number of people in the room and the probability is calculated. And secodly a formula for the probability as the same birthday as me Dave |
#6
Posted to microsoft.public.excel.misc
|
|||
|
|||
Birthday probability
O.K.
If A1 contains the number of people then: =1-(PERMUT(365,A1)/365^A1) -- Gary''s Student - gsnu200766 "Dave" wrote: Hi, Thank you for that but it really is only a repeat of what I have done,what I really wanted; and it might not be dooable, is a formula in a single cell that works out the probability for n where n is the number of people in the room. D "Gary''s Student" wrote: From Daytona Beach: http://go.dbc.edu/mathematics/walsh_...3E5943B498.pdf -- Gary''s Student - gsnu200766 "Dave" wrote: Hi, I can work out the probabilities for 2 people in the same room sharing a birthday by dragging formula down like so No People Different Same % 2 364 365 99.73% 0.274% 3 363 365 99.18% 0.820% 4 362 365 98.36% 1.636% But can anyone get this equation into a single formula where I imput n for the number of people in the room and the probability is calculated. And secodly a formula for the probability as the same birthday as me Dave |
#7
Posted to microsoft.public.excel.misc
|
|||
|
|||
Birthday probability
Absolutely superb and thank you, I had been assured by a maths type person;
but never believed it, that there wasn't an Excel formula. D "Gary''s Student" wrote: O.K. If A1 contains the number of people then: =1-(PERMUT(365,A1)/365^A1) -- Gary''s Student - gsnu200766 "Dave" wrote: Hi, Thank you for that but it really is only a repeat of what I have done,what I really wanted; and it might not be dooable, is a formula in a single cell that works out the probability for n where n is the number of people in the room. D "Gary''s Student" wrote: From Daytona Beach: http://go.dbc.edu/mathematics/walsh_...3E5943B498.pdf -- Gary''s Student - gsnu200766 "Dave" wrote: Hi, I can work out the probabilities for 2 people in the same room sharing a birthday by dragging formula down like so No People Different Same % 2 364 365 99.73% 0.274% 3 363 365 99.18% 0.820% 4 362 365 98.36% 1.636% But can anyone get this equation into a single formula where I imput n for the number of people in the room and the probability is calculated. And secodly a formula for the probability as the same birthday as me Dave |
#8
Posted to microsoft.public.excel.misc
|
|||
|
|||
Birthday probability
Sorry that was not clear to me!
-- Bernard V Liengme Microsoft Excel MVP www.stfx.ca/people/bliengme remove caps from email "Dave" wrote in message ... Hi, I'm confused, why do you say my data are incorrect? If I drag my formula down then for 23 people I get a 50.73% chance that 2 people share the same birthday and a 49.27% chance they don't 21 345 365 55.63% 44.369% 22 344 365 52.43% 47.570% 23 343 365 49.27% 50.730% 24 342 365 46.17% 53.834% 25 341 365 43.13% 56.870% The formula in Column D dragged down is D2 = =B2/C2 D3 = =B3/C3*D2 This is the dragged formula Mike "Bernard Liengme" wrote: Your data seems wrong. It is generally accepted that about 23 people give a 50% chance of 'clash' And after 100 it is essential 100% Have a look at: http://en.wikipedia.org/wiki/Birthday_paradox Do not try to compute 365! (in Excel FACT(365)) -- Bernard V Liengme Microsoft Excel MVP www.stfx.ca/people/bliengme remove caps from email "Dave" wrote in message ... Hi, I can work out the probabilities for 2 people in the same room sharing a birthday by dragging formula down like so No People Different Same % 2 364 365 99.73% 0.274% 3 363 365 99.18% 0.820% 4 362 365 98.36% 1.636% But can anyone get this equation into a single formula where I imput n for the number of people in the room and the probability is calculated. And secodly a formula for the probability as the same birthday as me Dave |
#9
Posted to microsoft.public.excel.misc
|
|||
|
|||
Birthday probability
Tue, 29 Jan 2008 04:52:00 -0800 from Dave
: I can work out the probabilities for 2 people in the same room sharing a birthday by dragging formula down like so But can anyone get this equation into a single formula where I imput n for the number of people in the room and the probability is calculated. http://www.tc3.edu/instruct/sbrown/stat/birthday.htm gives the formula and explains where it comes from. It makes the same simplifying assumption that you do, ignoring leap years. -- Stan Brown, Oak Road Systems, Tompkins County, New York, USA http://OakRoadSystems.com/ "If there's one thing I know, it's men. I ought to: it's been my life work." -- Marie Dressler, in /Dinner at Eight/ |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Days until birthday | Excel Worksheet Functions | |||
Getting 106 for Birthday Formula | Excel Discussion (Misc queries) | |||
Birthday calculations | Excel Discussion (Misc queries) | |||
Birthday Alert | Excel Discussion (Misc queries) | |||
Sorting by Birthday | Excel Discussion (Misc queries) |