Let height of water in tank be \(h\)
\(\text { So, } 4 P-P=\rho_w g h \quad \ldots (1)\)
\(\because \frac{3}{5}\) water taken out \(\frac{2}{5}\) th water is left to exert pressure
\(P^{\prime}=P+\frac{2}{5} \rho_w g h\)
\(\Rightarrow P^{\prime} =P+\frac{2}{5} \times 3 P\) [From eq. \((1)\)]
\(\Rightarrow P^{\prime} =\frac{11 P}{5}\)