Study the given letter series and answer the question that follows.
K I O X J E T R U L E B A C K J M N
How many such vowels are there each of which is immediately followed by atleast two consonants appearing together in the above series?

Vowels: A, E, I, O, U

Consonants: All other letters.

Mark vowels (bold) for clarity:

K I O X J E T R U L E B A C K J M N

We verify each vowel to see if it is immediately followed by at least two consonants:

I: Followed by O (vowel) → Does not meet the condition.

O: Followed by X (consonant), J (consonant) → Meets the condition.

E: Followed by T (consonant), R (consonant) → Meets the condition.

U: Followed by L (consonant), E (vowel) → Does not meet the condition.

A: Followed by C (consonant), K (consonant) → Meets the condition.

The vowels that satisfy the condition are: O, E and A.

Total: 3 vowels