what are the odds that two women in an office would start their period the same day?

Question

theyre the only women in the office. i just want to know statistically or mathematically, what are the odds of that happening...mathematicians, please tell me how to calculate it.thanks

Answer 1

well assuming that each has a 28 day cycle, and assuming that that there was no interaction

and assuming that it can be any day

then, given that one person starts on a given day, the chance of the other also starts that day is about 1 in 28

or about a 3.6% chance

so, if there are 100 offices out there with 2 women in them, 3 or 4 would be expected to have that happen for a chosen cycle

if you allow several months and several cycles, and there is any difference in the two cycles, then eventually, you expect any two to eventually coincide

if one person has a 27.5 day cycle and the other a 28, then each time they will get 1/2 day closer together until they are on the same day

the 1/28 chance case is for when one says out of the blue, i started today, and the other answers, me too

for that one time the probability is .036 per above

Answer 2

Depends on the size of the office. If there are five women in the office, then the probability is 1 - 27/28*26/28*25/28*24/28*23/28.

Answer 3

Menstrual synchronicity is probably a relic from our less evolved past. The advantage would be increased genetic diversity by making it more difficult for a dominant male to mate successfully with all females. Thus those who mated with other males would be more likely to get undivided protection (traditional male function) from those particular males. Just a little speculation as to why nature might have done this for the curious. If none of these women in your office gave off pheromones the answer would be straightforward.

Answer 4

Ignoring the biology that everyone else is fixated on,
It depends on how many women are in the office. If there are more than 28 women there, then of course two will start on the same day.

Answer 5

Menstrual periods occur once every 28 days, so all other things being equal, the odds are about 1 in 28.

But all other things are seldom equal. It has been shown that women living together for long periods (such as in a convent) will naturally tend to synchronize their menstrual cycles.

Answer 6

1/28

Answer 7

When women, within a family or an office, spend a lot of time together it's very likely their periods will become in sync with each other. It happens a lot!

Answer 8

Odds are pretty great of that happening, been there, done that. Good thing we both did not call in sick because of really bad "cramps"!!! There are many of us women out there, you should know the odds are against "ya'll" of this happening! Sorry any men out there, want to change roles?

Answer 9

The odds are pretty good.... the less dominant females body will adjust its time table to the alpha females schedule. Personal experience.

Answer 10

Shiara is right...when women live together (and in this case, spend 8+hours together at work) their menstrual cycles start to converge together to be near the same times.