Answer :
Given the number:
[tex]7,248,531[/tex]notice that the even and odd digits that are in this number are:
[tex]\begin{gathered} odd\colon7,5,3,1 \\ \text{even:}2,4,8 \end{gathered}[/tex]there are 4 odd digits and 3 even digits, then the ratio of odd to even is:
[tex]\text{odd to even=}\frac{4}{3}=4\colon3[/tex]