Question

Sarada and Hamida are friends. What is the probability that both will have (i) different birthdays? (ii) the same birthday? (ignoring a leap year).

Answer 1

Hi ,

Out of the two friends , one girl ,say

Sarada's birthday can be any day of

the year .

Hamida's birthday can also be any

day of 365 days in the year .

We assume that these 365 outcomes

are equally likely.

i ) If Hamida's birthday is different from

Sarada's , the number of favourable

outcomes for her birthday is

365 - 1 = 364

So, P( Hamida's birthday is different

from Sarada's birthday ) = 364/365

ii ) P( Sarada and Hamid have the same

birthday ) = 1 - P

( both have different birthdays )

= 1 - ( 364/365 )

[ Using P( E bar ) = 1 - P( E )

= 1/365

I hope this helps you.

: )