2 votes 2 votes There are 60 persons in a room.We have choosen 10 person at random. What is the probability that exactly 2 person among them have same birthday? Probability probability birthday + – srestha asked Mar 2, 2018 srestha 744 views answer comment Share Follow See all 6 Comments See all 6 6 Comments reply Show 3 previous comments Angkit commented Mar 2, 2018 reply Follow Share 10C2 -> "we do not know which person birthdays are same from the 10" 0 votes 0 votes Akhilesh Singla commented Mar 2, 2018 reply Follow Share But by defining probability of each of 10 persons' birthday, I am unable to understand why we still need to make a selection by using 10C2. If we were to define only two probabilities then I think selection would be required first. 0 votes 0 votes Angkit commented Mar 2, 2018 reply Follow Share the 10 people can arrange themselves 0 votes 0 votes Please log in or register to add a comment.
3 votes 3 votes 60C10 * 10C2 *[ (1/365)^2 * (364/365)(363/365)(362/365)(361/365)(360/365)(359/365)(358/365)(357/365) ] selected 10 from 60.And then from 10 we are free to select any two fot same birthday Angkit answered Mar 2, 2018 • edited Mar 2, 2018 by Angkit Angkit comment Share Follow See all 10 Comments See all 10 10 Comments reply Show 7 previous comments srestha commented Mar 3, 2018 reply Follow Share yes.. 0 votes 0 votes Angkit commented Mar 3, 2018 reply Follow Share If we see term (364/364)=1 //probability is 1 So, we add all probability,it will be greater than 1? //That's not possible 0 votes 0 votes Tarun kushwaha 1 commented Mar 3, 2018 reply Follow Share @srestha ma'am yes that link make sense thanks.. now it's clear. @Angkit in your solution how are you choosing which day they have same birthday.. i.e we have to choose this as 365C1. 0 votes 0 votes Please log in or register to add a comment.
