Someone brought up in conversation that three of her friends had consecutive birthdays (such as November 10, 11, and 12), and I wanted to figure out how likely that is for any randomly selected three people, assuming that birthdays are randomly distributed and the birthdays of two people in a sample are independent. My answer:
= possible arrangement of consecutive birthdays / possible arrangements all birthdays = 365 / 365^3 = 0.0000075
Does that sound about right? Or am I missing something?