1)
Australia
4 consonants (s, t, r, l)
5 vowels (a, u, a, i, a)
consonants : vowels = 4 : 5
2)
123446789
4 odd digits (1, 3, 7, 9)
5 even digits (2, 4, 4, 6, 8)
odd digits : even digits = 4 : 5
3)
Elizabeth
5 consonants (l, z, b, t, h)
4 vowels (e, i, a, e)
consonants : vowels = 5 : 4
4)
234567899
5 composite digits (4, 6, 8, 9, 9)
4 prime digits (2, 3, 5, 7)
composite digits : prime digits = 5 : 4
The situations that have a ratio of 4:5 are: consonants to vowels in the name Australia and odd digits to even digits in 123446789.