If 5 -letter words'' are formed using the letters A, B, C, D, E, F, G, how many such words are possible for each of the following conditions? a. No condition is imposed.
b. No letter can be repeated in a word.
c. Each word must begin with the letter A and letters can be repeated.
d. The letter C must be at the end and letters can be repeated.
e. The second letter must be a vowel and letters can be repeated.