Given ratio:
[tex]\frac{3}{2}\text{ : }\frac{1}{4}[/tex]Multiply both sides by the L.C.M of their denominator
The L.C.M of 2 and 4 is 4
Hence:
[tex]\begin{gathered} 4\text{ }\times\frac{3}{2}\text{ : 4}\times\frac{1}{4} \\ 6\text{ : 1} \end{gathered}[/tex]