Question

For PLANETS, find the number of :
4-letter words which must include a L and A

For MAMMALS, find the munber of:
a) 7-letter words
b) 7-letter word beggining with MA
c) 4-letter words
i) all letters different
ii) 2 letters same,2 different
iii) 2 pairs same leeters
iv) 3 letters same

Answer 1

Can letters be used twice? Do the words have to be in the dictionary?

Answer 2

no

Answer 3

In that case, for PLANETS, the possible four-letter combinations (in any order) are 5 x 4 = 20. For each combination, there are 4! = 24 ways (permutations) for arranging the letters. That makes 20x24 = 480 possible "words". Most will not be in the dctionary.

Try your own reasoning with the MAMMALS problem. We will be glad to critique your work.