We have a 630 ml of mixture of milk and water in the ratio 7:2. How much water must be added to
make the ratio 7:3?	Options:
A) 70 ml
B) 60 ml
C) 80 ml
D) 50 ml
E) None of these
Explanation :   concentration of water in mixture1 = 2/9 (Since the ratio of milk and water = 7:2) ---item(1)   concentration of water in pure water= 1 ---item(2)   Now the above mentioned items are mixed to form a mixture2 where milk and water ratio = 7: 3   =&gt;concentration of water in mixture2 = 3/10   By the rule of alligation, we have   concentration of water   in mixture1 : 2/9 concentration of water   in pure water : 1   Mean concentration   3/10   1 - 3/10 = 7/10 3/10 - 2/9 = 7/90   =&gt; Quantity of mixture1 : Quantity of water = 7/10 : 7/90 = 1/10 : 1/90 = 1 : 1/9   Given that Quantity of mixture1 = 630 ml   =&gt; 630 : Quantity of water = 1 : 1/9   ⇒Quantity of water = 630×19=70 ml   70 mlnswer : Option 70 ml
<result>A</result>
We have a 630 ml of mixture of milk and water in the ratio 7:2. How much water must be added to
make the ratio 7:3?