This is not a trick question and seems so easy to me, but I was told I
was wrong.  You can count people born on Feb. 29th or not, I don't
care. The question is: "What is the most amount of people you can have
in a room without the same birthdate repeating itself?"

---

Clarification of Question by fredg2004-ga on 07 May 2005 11:36 PDT

pinkfreud and justaskscott...i have a dilemma....i will take either
one of your answering the question. if i take both of you i will give
you  3dollars each and 5 stars because you both answered my question.
pink, you answered first, but justaskscott gave that birthday
paradox.... both of your answers confirmed my answer but that is
besides the point. you both gave an answer. please advise and thanks

---

Request for Question Clarification by pinkfreud-ga on 07 May 2005 13:33 PDT

Since my colleague justaskscott did some research and provided a link
to a related problem, I think he should post the answer and collect
the fee. My remark was just off the top of my head.

---

Request for Question Clarification by justaskscott-ga on 07 May 2005 13:53 PDT

Since we're talking about probability, I suggest that fredg2004 flip a
coin, with heads for pinkfreud and tails for me.  If it's heads, then
fredg2004 can award the answer to pinkfreud.  If it's tails, then I'll
answer.

It's what I do when I can't decide.

---

Clarification of Question by fredg2004-ga on 07 May 2005 16:02 PDT

i am not talking about probability. i am talking about a question that
has an answer. i said it was not a trick question. i thought the
answer was 366 or 367 but the person who said it wasn't is a college
math professor. i did not mean to make this hard. i said it was not a
trick question. i should have trusted my instincts. since pink
answered first, i am paying him 6.00 and if he wants to split
it...fine if not keep it...five stars also.....man this was hard work
and thanks.....pink please do what you have to so i can pay you......

---

Request for Question Clarification by justaskscott-ga on 07 May 2005 16:44 PDT

Sorry about that: I meant to say that my proposed answer concerns
probability, though it ends with certainty.

In any case, I think that pinkfreud can provide an answer with the
certainty you need.

---

Clarification of Question by fredg2004-ga on 07 May 2005 17:07 PDT

i got an email from google saying i had to answer the last that was
sent by justaskscott. i flipped the coin before my last outburst. it
came up pink....after rereading my last....it seemed that i was rude.
i did not mean to be....but...but......someone tell me who gets the
money. thanks

I'm glad to have been able to help you with this. 

Here are a few links to discussions of other problems involving birthdays:

Able2Know Forums
http://www.able2know.com/forums/about21424.html

TES Mathematics Staffroom
http://www.tes.co.uk/section/staffroom/thread.aspx?story_id=2089580&path=/mathematics/&threadPage=4&messagePage=2

Ivars Peterson's MathTrek: Birthday Suprises
http://www.maa.org/mathland/mathtrek_11_23_98.html

Here is a list of all the possible days upon which a person might have been born:

1)   January 1
2)   January 2
3)   January 3
4)   January 4	
5)   January 5
6)   January 6
7)   January 7	
8)   January 8
9)   January 9 
10)  January 10	
11)  January 11
12)  January 12
13)  January 13
14)  January 14	
15)  January 15	
16)  January 16 
17)  January 17
18)  January 18 
19)  January 19
20)  January 20
21)  January 21
22)  January 22
23)  January 23
24)  January 24
25)  January 25	
26)  January 26	
27)  January 27	
28)  January 28
29)  January 29
30)  January 30 
31)  January 31 
32)  February 1
33)  February 2
34)  February 3 
35)  February 4 
36)  February 5
37)  February 6
38)  February 7
39)  February 8 
40)  February 9 
41)  February 10 
42)  February 11 
43)  February 12 
44)  February 13
45)  February 14
46)  February 15
47)  February 16
48)  February 17	
49)  February 18	
50)  February 19
51)  February 20
52)  February 21
53)  February 22
54)  February 23
55)  February 24
56)  February 25
57)  February 26
58)  February 27
59)  February 28
60)  February 29
61)  March 1
62)  March 2
63)  March 3
64)  March 4
65)  March 5 
66)  March 6 
67)  March 7 
68)  March 8
69)  March 9
70)  March 10
71)  March 11
72)  March 12 
73)  March 13 
74)  March 14
75)  March 15
76)  March 16
77)  March 17 
78)  March 18
79)  March 19	
80)  March 20
81)  March 21
82)  March 22
83)  March 23 
84)  March 24
85)  March 25
86)  March 26
87)  March 27
88)  March 28
89)  March 29 
90)  March 30	
91)  March 31 
92)  April 1	
93)  April 2
94)  April 3
95)  April 4
96)  April 5 
97)  April 6	
98)  April 7 
99)  April 8 
100) April 9
101) April 10
102) April 11
103) April 12 
104) April 13 
105) April 14
106) April 15
107) April 16
108) April 17
109) April 18
110) April 19
111) April 20
112) April 21	
113) April 22
114) April 23	
115) April 24
116) April 25
117) April 26
118) April 27 
119) April 28 
120) April 29
121) April 30	
122) May 1
123) May 2
124) May 3	
125) May 4 
126) May 5 
127) May 6
128) May 7
129) May 8 
130) May 9 
131) May 10
132) May 11
133) May 12
134) May 13
135) May 14
136) May 15
137) May 16
138) May 17
139) May 18 
140) May 19
141) May 20	
142) May 21
143) May 22
144) May 23	
145) May 24	
146) May 25
147) May 26
148) May 27
149) May 28 
150) May 29
151) May 30
152) May 31
153) June 1
154) June 2
155) June 3
156) June 4
157) June 5
158) June 6
159) June 7	
160) June 8 
161) June 9 
162) June 10
163) June 11	
164) June 12
165) June 13
166) June 14
167) June 15
168) June 16
169) June 17	
170) June 18
171) June 19
172) June 20 
173) June 21
174) June 22 
175) June 23 
176) June 24
177) June 25
178) June 26 
179) June 27
180) June 28
181) June 29 
182) June 30	
183) July 1 
184) July 2
185) July 3
186) July 4 
187) July 5
188) July 6
189) July 7
190) July 8
191) July 9
192) July 10	
193) July 11
194) July 12
195) July 13
196) July 14 
197) July 15
198) July 16
199) July 17
200) July 18	
201) July 19 
202) July 20
203) July 21
204) July 22	
205) July 23 
206) July 24 
207) July 25	
208) July 26
209) July 27
210) July 28 
211) July 29
212) July 30
213) July 31
214) August 1 
215) August 2
216) August 3
217) August 4	
218) August 5
219) August 6
220) August 7	
221) August 8
222) August 9
223) August 10
224) August 11
225) August 12
226) August 13
227) August 14 
228) August 15
229) August 16
230) August 17
231) August 18
232) August 19 
233) August 20
234) August 21 
235) August 22
236) August 23
237) August 24
238) August 25
239) August 26
240) August 27	
241) August 28
242) August 29
243) August 30
244) August 31 
245) September 1
246) September 2 
247) September 3 
248) September 4
249) September 5
250) September 6 
251) September 7
252) September 8
253) September 9 
254) September 10
255) September 11 
256) September 12 
257) September 13 
258) September 14
259) September 15
260) September 16
261) September 17
262) September 18
263) September 19
264) September 20
265) September 21
266) September 22
267) September 23
268) September 24
269) September 25 
270) September 26
271) September 27
272) September 28
273) September 29
274) September 30	
275) October 1
276) October 2
277) October 3
278) October 4
279) October 5
280) October 6
281) October 7
282) October 8
283) October 9
284) October 10
285) October 11
286) October 12
287) October 13
288) October 14
289) October 15
290) October 16	
291) October 17 
292) October 18 
293) October 19
294) October 20
295) October 21
296) October 22
297) October 23
298) October 24
299) October 25 
300) October 26
301) October 27
302) October 28
303) October 29
304) October 30
305) October 31
306) November 1
307) November 2
308) November 3
309) November 4
310) November 5 
311) November 6
312) November 7
313) November 8
314) November 9	
315) November 10 
316) November 11 
317) November 12
318) November 13
319) November 14
320) November 15
321) November 16
322) November 17
323) November 18
324) November 19
325) November 20
326) November 21	
327) November 22
328) November 23
329) November 24 
330) November 25 
331) November 26	
332) November 27
333) November 28
334) November 29
335) November 30 
336) December 1 
337) December 2
338) December 3
339) December 4
340) December 5
341) December 6
342) December 7
343) December 8
344) December 9
345) December 10
346) December 11
347) December 12
348) December 13
349) December 14
350) December 15	
351) December 16
352) December 17
353) December 18 
354) December 19
355) December 20
356) December 21
357) December 22
358) December 23
359) December 24
360) December 25
361) December 26	
362) December 27 
363) December 28 
364) December 29
365) December 30
366) December 31

It is within the realm of possibility that 366 people, each born on a
different date listed above, might occupy a room. Once a 367th person
entered the room, there would be a certainty of a shared birthday.

Best regards,
pinkfreu

thanks pinkfreud....this should come to 5.00 i guess. i will tip you 1.35

It seems to me that there are 366 possible birthdays (one for each day
of the year, plus February 29th for leap year babies), so you could,
in theory, have 366 people in a room without any birthdays in common.
This would be highly unlikely to happen, of course.

When they say birthdate do they also mean year?  I share a  birthday
with Paul McCartney but there are 20 years between us.

Well... as a Christian, I would say that modern man's days cannot exceed 120 years.

120 years times 365 days plus 1 extra day every four years equals the
number of people.

120 x 365 + (365/4)= answer

120 x 365 + (91.25)= answer

43891.25 would be the answer.
Guessing that the pregnant woman somewhere in the room's fetus doesn't
count, let's round that to 43,891.  So if you had an arena, that would
be my best guess for an answer.

Hope this helps!

Krysten <><

The person who said you were wrong might be thinking of a similar
question concerning the probability that at least two people in a room
will share the same birthday (i.e., month and day, regardless of
year).  The probability is over 50% for 23 people, and over 99% for 60
people.

"birthday paradox"
Answers.com
http://www.answers.com/topic/birthday-paradox

But it's still not 100% (even though it's very close) until you reach 367 people.

Thank you very much for the five stars and the nice tip!

~pinkfreud