The ratio of milk and water in a mixture is 2 : 1. How much part of the mixture should be replaced by water so that the ratio of milk and water becomes 5 : 3.

\(\frac{1}{16}\)

                                    Milk               Water           Total

initial Ratio                       2          :        1      =        3

Ratio after drawn off         2          :        1      =        3 ........(i)

Ratio after water added     5          :         3      =        8 ........(ii)

In (i) and (ii) milk should be same because in these steps only water is added. Therefore, (i) × 5 & (ii) × 2           

                                    Milk                Water          Total

Ratio after drawn off        10          :        5      =        15

Ratio after water added    10          :        6      =        16

                                                           + 1               16 (Final/initial Qty.)

Mixture to be removed = \(\frac{1}{16}\)