CAT Exam 2021 Slot 2 Solved Paper

liters is drawn every times.Let initial volume be V, final be F for milk,
The formula is given by : $\mathrm{F}=\mathrm{V},{\left(1-\frac{\mathrm{k}}{\mathrm{V}}\right)}^{\mathrm{n}}$ n is the number of times the milk is drawn and replaced.
So we get $\mathrm{F}=\mathrm{V}{\left(1-\frac{\mathrm{k}}{\mathrm{V}}\right)}^2$
Here $\mathrm{K}=9$
We get
$\frac{16}{25}\mathrm{V}=\mathrm{V}{\left(1-\frac{9}{\mathrm{V}}\right)}^2$
We get $1-\frac{9}{\mathrm{V}}=\frac{4}{5}\mathrm{or}\frac{4}{5}$
$\mathrm{V}=5$, but this is not possible because 9 liters is drawn every time.
Hence : $1-\frac{9}{\mathrm{V}}=\frac{4}{5},\mathrm{V}=45\mathrm{liters}$