Question

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

Answer 1

Let the required number of milliliters of alcohols be x ml.

Given 15 % of 400 ml should be added with 100 % of pure alcohol.

Hence 400(15 %) + x(100 %) = (400+x) (32 %)

⇒ 400 × 15/100 + x = (400 + x) × (32/100)

⇒ 60 + x = 128 + (8x/25)

⇒ x - 8x/25 = 128 - 60

⇒ 17x/25 = 68

⇒ x = (68 × 25)/17

⇒ x = 1700/17

x = 100 ml   Answer.

Answer 2

QUESTION

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

ANSWER

let the required quantity of alcohol be X ml.

Now, According to the question

15% of 400ml is to be added with 100% of pure alcohol.

So we get=>>

400(15%) + x(100%) = (400+x)32%

=>(400×15)/(100)+ x = ((400+x)×32)/100

=>60+x = 128 + (8x/25)

=>x - 8x/25 = 128-60

=>17x/25 = 68

=>X = (68× 25)17

=>x = 1700/17

=>x = 100ml

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

thanks