Explanation

(c) Pressure at neck of bottle
$p_{1} = \frac{F_{1}}{A_{1}} = \frac{F_{1}}{{\pi\ r}_{1}^{2}}$
Similarly, pressure at bottom of bottle
$p_{2} = \frac{F_{2}}{A_{2}} = \frac{F_{2}}{{\pi\ r}_{2}^{2}}$
According to Pascal’s law, liquids transmits pressure equal in all directions.
$\therefore$ $\frac{F_{2}}{A_{2}} = \frac{F_{2}}{{\pi\ r}_{2}^{2}}\ or\ F_{2} = F_{1} \times \left( \frac{r_{2}}{r_{1}} \right)^{2}$
$= 12 \times \left( \frac{15}{3} \right)^{2} = 12 \times 25 = 300N$