Question

A solution of salt and water contains 5% salt by weight. Of it 20 kg water evaporates and the solution now contains 15% of salt. Find the original quantity of solution.

Answer 1

Answer:

et the amount of water in the original solution =x kg.

Then the amount of salt present in 15% of this solution =  

100

15x

​  

kg=  

20

3x

​  

 kg.

After 30 kg water evaporates, the amount of water =(x=30) kg.

So, the new concentration =  

x−30

20

3x

​  

 

​  

×100.

Then, by the given condition,

x−30

20

3x

​  

 

​  

×100=20

⇒4x−120=3x

⇒x=120 kg

So, the quantity of the original solution =120 kg.