Answer: [tex]377.3\ kPa[/tex]
Explanation:
Given
Water column height [tex]h=25\ cm[/tex]
After oil is poured, the total height becomes [tex]h'=40\ cm[/tex]
Pressure at the bottom will be the sum due to the water and oil column
Suppose the density of the oil is [tex]\rho=900\ kg/m^3[/tex]
Pressure at the bottom
[tex]\Rightarrow P=10^3\times g\times 25+900\times g\times 15\\\Rightarrow P=100g[250+135]\\\Rightarrow P=3773\times 100\ Pa\\\Rightarrow P=377.3\ kPa[/tex]