Question

A girl loves to receive mail, but only 5% of the family's letters are addressed to her. The recipient of each letter is independent of all other letters. Find the mean number of letters received by other members of the family prior to her receiving her second letter.

Answer 1

Negative Binomial

Explanation:

The girl receives only 5% of mail which are addressed to her. Rest of 95% mails belong to other family members.

P (X) = 5%

P (X) = 95 / 5

P (X) = 19

The family receives 19 mails out of which only 5% will address the girl. The all other mails belong to the other family members.