Question

3 4 5. How much pure alcohol must be added to 400 ml of a 15% solution to make its strength 32%?​

Answer 1

Answer:

How much pure alcohol must be added to 400 mL of a 15% solution to make its strength 32%. Therefore, 100 mL of alcohol should be added to make the strength 32%. This is the required answer.

Answer 2

Answer:

The amount of alcohol in 400ml solution of 15% strength

=400×

100

15

ml=60ml

Let the required amount of alcohol to be added =x ml.

It will increase the amount of the solution by x ml.

∴ The amount of alcohol now =(60+x)ml

and the amount of the solution=(400+x)ml.

Then, the strength =32%=

400+x

60+x

=

100

32

⇒25x+1500=3200+8x

⇒17x=1700

⇒x=100.

So, the required amount of pure alcohol to be added =100ml