# From 40 liters of 2 : 3 milk-water solution, 8 liters are withdrawn and replaced by 8 liters of milk. What is the approximately minimum number of times should we perform the operation of withdrawing and replacing so that the milk concentration is at least 60%? Option 1) 4Option 2) Option 3) Option 4) Option 5)

$\left ( 1-\frac{8}{40} \right )^{n}= \frac{final}{initial}$
$\left ( \frac{4}{5} \right )^{n}= \frac{2}{3}$
$N=2$
$0.64\approx 0.6$