Two wires $W_1$ and $W_2$ have the same radius $r$and respective, densities ${\rho }_1$ and ${\rho }_2$, such that ${\rho }_2=4{\rho }_1$ . They are joined together at the point $O$, as shown in the figure. The combination is used as a sonometer wire and kept under tension $T$. The point $O$ is midway between the two bridges. When a stationary wave is set up in the composite wire, the joint is found to be a node. The ratio of the number of antinodes formed in $W_1$ to $W_2$ is