(b) A computer password, which must contain 6 characters, is to be chosen from the following

10 characters:

Symbols ? ! *

Numbers 3 5 7

Letters W X Y Z

Each character may be used once only in any password. Find the number of possible passwords

that may be chosen if

(i) there are no restrictions, [1]

(ii) each password must start with a letter and finish with a number, [2]

(iii) each password must contain at least one symbol. [3]

For no iii) each password must contain at least one symbol, I did3x 7 x 6 x 5 x 4 x 3+3 x 2x 7 x 6 x 5 x 4+3 x 2 x 1x 7 x 6 x 5 , is this correct?