A vessel is full with 63 litres of milk. 9 litres milk is taken out and replaced by same amount of water and further 7 litres mixture is taken out and replaced by same amount of water. Find at the end of 2nd process the amount of water in the mixture?

15 L

i) \(\frac{9}{63}\) = \(\frac{1}{7}\)  ⇒ Remaining part = \(\frac{6}{7}\),

ii) \(\frac{7}{63}\) = \(\frac{1}{9}\) ⇒ Remaining part = \(\frac{8}{9}\)

Now,

Milk after 2 process = 63 × \(\frac{6}{7}\)  × \(\frac{8}{9}\) = 48 ltr.

∴ Water after 2 process = 63 - 48 = 15 Ltrs.