of the 15 letter passwords formed by mixing 9 letters (from A to Z, allowing repeats) and 6 numbers (from 1 to 9, without repeats), I pick one at random

7. (a) Of the 15-letter passwords formed by mixing 9 letters (from A to Z, allowing repeats) and 6 numbers (from 1 to 9 without repeats), I pick one at random. Determine: i. Prob (my password begins with A and includes at least three even digits) ii. Prob (my password includes 4 A's, 3 B's, and 2 C's, and no A appears anywhere between the two C's)