If 4 consecutive letters are selected at random from the English alphabet, then the probability that one of the letters is a vowel is ?
Choose the correct choice from the following choices: A) 13 / 23 B) 16 / 23 C) 11 / 23 D) 17 / 23 E) 18 / 23

Rationale: total no . of ways of selecting 4 consecutive letters = > 23 [ like abcd , bcde , efgh , . . etc ] no . of ways of having one is a vowel = > abcd , bcde , cdef , defg , efgh , fghi , ghij , hijk , ijkl , lmno , mnop , nopq , opqr , rstu , stuv , tuvw , uvwx . . . = 17 p ( one of letter is vowel ) = 17 / 23 answer : d
Answer: D