Question

How much pure alcohol must be added to 400 ml of a 15% solution to make it strength 32%

Answer 1

Answer:

100mL of alcohol should be added.

Step-by-step explanation:

Let amount of alcohol to be added be x.

Amount of alcohol in the 400 mL solution = (15/100)×400=60 mL

Now,

Add x mL alcohol to the solution.

((60mL+x)/(400mL+x))×100=32

(60mL+x)/(400mL+x)=32/100=8/25  

1500mL+25x=3200mL+8x

17x=1700mL

x=100mL

So, 100mL of alcohol should be added.

Answer 2

Answer:

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