Jan |
Feb |
March |
April |
May |
June |
July |
Aug |
Sept |
Oct |
Nov |
Dec |
${\color{DarkRed} S}$ |
${\color{DarkRed} S}$ |
${\color{DarkRed} S}$ |
${\color{DarkRed} S}$ |
${\color{DarkRed} S}$ |
${\color{DarkRed} S}$ |
${\color{DarkRed} S}$ |
${\color{DarkRed} S}$ |
${\color{DarkRed} S}$ |
${\color{DarkRed} S}$ |
${\color{DarkRed} S}$ |
${\color{DarkRed} S}$ |
${\color{DarkOrange} S}$ |
${\color{DarkOrange} S}$ |
${\color{DarkOrange} S}$ |
${\color{DarkOrange} S}$ |
${\color{DarkOrange} S}$ |
${\color{DarkOrange} S}$ |
${\color{DarkOrange} S}$ |
${\color{DarkOrange} S}$ |
${\color{DarkOrange} S}$ |
${\color{DarkOrange} S}$ |
${\color{DarkOrange} S}$ |
${\color{DarkOrange} S}$ |
${\color{Green} S}$ |
${\color{Green} S}$ |
${\color{Green} S}$ |
${\color{Green} S}$ |
${\color{Green} S}$ |
${\color{Green} S}$ |
${\color{Green} S}$ |
${\color{Green} S}$ |
${\color{Green} S}$ |
${\color{Green} S}$ |
${\color{Green} S}$ |
${\color{Green} S}$ |
${\color{Magenta} S}$ |
${\color{Magenta} S}$ |
${\color{Magenta} S}$ |
${\color{Magenta} S}$ |
${\color{Magenta} S}$ |
${\color{Magenta} S}$ |
${\color{Magenta} S}$ |
${\color{Magenta} S}$ |
${\color{Magenta} S}$ |
${\color{Magenta} S}$ |
${\color{Magenta} S}$ |
${\color{Magenta} S}$ |
${\color{Teal} S}$ |
${\color{Teal} S}$ |
${\color{Teal} S}$ |
${\color{Teal} S}$ |
${\color{Teal} S}$ |
${\color{Teal} S}$ |
${\color{Teal} S}$ |
${\color{Teal} S}$ |
${\color{Teal} S}$ |
${\color{Teal} S}$ |
${\color{Teal} S}$ |
${\color{Teal} S}$ |
Procedure :-
select $12$ students and then put them in $1$ slot each like $1^{st}$ Jan $, 2^{nd}$ in Feb$, 3^{rd}$ in March and so on.
repeat the above step $5$ times.
so total students selected till now $= 12\times 5 =60$ and in each month we have $5$ students.
now if we select $1$ more student then his birthday can be in any of the given $12$ months.
say his birthday is in December then we can
guarantee that there are at least $6$ students whose birthdays fall in the same month
so total students required $= 60 +1 =61.$