(a)[3]
Find the number of distinct arrangements of the 9 letters in the word ANDROMEDA in which no consonant is beside another consonant. (The letters D, M, N and R are consonants and the letters A, E and O are not consonants.)
(b)[3]
Find the number of different arrangements of the 9 letters in the word ANDROMEDA in which there is an A at each end and the Ds are not adjacent.
(c)[4]
Four letters are chosen at random from the 9 letters in the word ANDROMEDA. Find the probability that the chosen set contains at least one D and exactly one A.