Question

How much pure alcohol must be added to 400 ml of a 15% solution to make its strength 32%? Give reason

Answer 1

Original amount of alcohol = 400 ml

Percentage of alcohol in the solution = 15%

Let x ml alcohol is added to the solution

∴ Amount of alcohol = (60 + x) ml

Amount of solution = (400 + x) ml

Given that the percentage of alcohol in the solution is 32
Thus, approximately 179.4 ml of alcohol is added to the solution.

 



 


 

Answer 2

Hi mate,

Solution :

=> Volume of alcohol in 400 ml solution

➾ 0.15 × 400 ml

=> Volume of alcohol in 400 ml solution

➾ 60 ml

=> Volume of others liquid

➾ 340 ml

=> Let x ml of alcohol is added to make it 32% strong

=> Then, volume of alcohol

➾ 60+x ml

=> Volume of other liquid

➾ 340 ml

=> Volume of solution

➾ 400 + x ml

➾ 0.32 × (400 + x) = 60 + x

➾ 128 + 0.32x = 60 + x

➾ 0.68x = 68

➾ 68x = 6800

➾ x = 100 ml ...

Answer : 100 ml pure alcohol must be added to 400ml of a 15% solution to make it's strength 32%

i hope it helps you