A soap bubble having radius of $1\,\text{mm}$ is blown from a detergent solution having a surface tension of $2.5 \times 10^{-2}\,\text{N}\,\text{m}^{-1}$. The pressure inside the bubble equals at a point $Z_0$ below the free surface of water in a container. Taking $g = 10\,\text{m}\,\text{s}^{-2}$, density of water $= 10^3\,\text{kg}\,\text{m}^{-3}$, the value of $Z_0$ is