In how many ways can $5$ girls and $3$ boys be seated in a row so that no two boys are together?

The number of words which can be formed from the letters of the word $MAXIMUM$,if two consonants cannot occur together,is

How many even numbers of $3$ different digits can be formed from the digits $1, 2, 3, 4, 5, 6, 7, 8, 9$ (repetition is not allowed)?

There are $4$ parcels and $5$ post-offices. In how many different ways can the registration of the parcels be made?

Out of $10$ persons,$A, B$,and $C$ are to speak at a function. If $A$ wants to speak before $B$ and $B$ wants to speak before $C$,in how many ways can they speak?

$A$ number lock consists of three rings. If the $1^{st}$ ring is marked with digits $0$ to $9$,the $2^{nd}$ ring is marked with prime numbers greater than $2$ but less than $30$,and the $3^{rd}$ ring is marked with all vowels,find the total number of unsuccessful attempts.