Find the probability that among seven persons at least two were born on the same day. (By day I don't mean date, I mean Mon, Tues, Wed, Thurs, Fri, Sat or Sun)
The probability that among seven persons at least two were born on the same day = 1 - Probability that all seven persons were born on different days.
Number of ways in which all seven persons were born on different days = Number of ways of filling n = 7 blank spaces(here days) with n = 7 distinct things(here persons) such that each blank space is filled with one thing = = = 7! = 5040
Each person could be born in any of the seven days.
Therefore the total number of ways the seven persons were born on seven days =
The probability that all seven persons were born on different days = = 0.00612
Therefore the probability that among seven persons at least two were born on the same day = 1 - 0.00612 = 0.99388
Get Answers For Free
Most questions answered within 1 hours.