A social network program assigns each person who joins a 7 letter password consisting of 7 different letters chosen completely at random from the 26 letters of the alphabet.

(1) You and your two best friend join the network. What is the probability that the first letter of your password is the same as the first letter of one of your friend's passwords, but different from the first letter of the other friend's passwords?

(2) Your social network group consists of 8 people. What is the probability that the first letter of each of your eight passwords is different from anyone else's?

(3) We found an approximate way to find the answer in the previous question, but which makes the calculation simpler. Make this calculation.