Since the total number of letters is 26, the number of letters without G would be 25.

(a) Number of 4 letter words which can be formed out of 25 would be 25x25x25x25, if repetitions are allowed.

25x25x25x25 = 390,625

(b) If the 4 letter words contain one G, the number of words which can be formed will be 25x25x25 = 15625, repetitions being allowed.

If the 4 letter words contain two Gs, the number of words which can be formed will be 25x25=625

If the 4 letter words contain three Gs, the number of words which can be formed will be =25

If the 4 letter words contain four Gs, the number of words which can be formed will be= 1

Hence total number of words containing at least one G = 15625+ 625 +25 + 1

= 16276

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