A can of water and milk mixture contains 60% milk. A part of this mixture is replaced by another mixture containing 50% milk and the percentage of milk was found to be 52%. The quantity of mixture replaced is:

$\frac{4}{5}$

Using mixture and allegations,

⇒ Ration of 60% milk to 50% milk is = 2 : 8 = 1 : 4,

⇒ Now the quantity of mixture replaced is,

⇒ 1 - \(\frac{1}{1+4}\)

⇒ \(\frac{4}{5}\)

Therefore the quantity of mixture replaced is \(\frac{4}{5}\).