The total number of alphabets are 26.
The total number of vowels are 5.
Th repetition is allowed.
The possible outocme for all to be vowels are,
[tex]PO=5^4[/tex][tex]PO=625[/tex]The total outcome is,
[tex]TO=26^4[/tex]Therefore, the probability that all 4 will be vowels ,
[tex]P=\frac{625}{456976}[/tex][tex]P=0.00137[/tex]The probability is 0.137 %.
