Question

100 mL of a solution with a S.G. of 1.30 is mixed with how many milliliters of another solution with a S.G. of 1.15 to make a solution with a S.G. of 1.20. How many milliliters of this 1.15 solution are used?

How is this worked? Answer should be 200

Answer 1

100 ml solution having SG 1.30

Another solution let it be X having SG 1.15

These 2 combining to form a solution having SG 1.20

Here we have to find out the value of X ...

Using allegation method we can solve the problem easily

100 ml X

1.30 1.15

  

1.20

0.5 : .10

1 : 2

so that the ratio becomes 1:2

Here 1 corresponds to 100

so automatically X corresponds to 200