Question

The amount of alcohol to be added to 400 ml of a 15% solution to make its strength 32% is what ?

Answer 1

Let x be the amount of alcohol added 

There is 60 mL of alcohol in the 15% solution because 60/400 = 0.15 

The second solution will have 60+x mL of alcohol and 400+x mL in total. 

So (60+x)/(400+x) = 0.32 
60+x = 128+0.32x 
0.68x = 68 
x = 100 mL 

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