Question

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

Answer 1

Out of two frnds, one girl say, Savita's bday can be any day of the year. Now, Hamida's bday can also be on any day out of 365 days in the Year.

We assume that these 365 outcomes are equally likely.
(i) If Hamida's bday is different from savita's, the no. Of favorable outcomes for her bday is 365-1= 364

So, P(Hamida' bday is diffrent from Savita's bday)=364/365

(ii) P(Savita and Harmida have the same bday)=
1-P(Both have diffrent bdays)
=1-(364/365) [ using P(not event)=1-P(E)]
=1/365

Hope it help.....

Answer 2

Answer:

P( different birthday's) = 365-1 /365 = 364/365

P( same birthday's) = 1-364 /365 =1/365