Question

if 10 litre solution of water and alcohol containing 10% alcohol is to be made 20% alcohol solution. find the volume of alcohol to be added

Answer 1

Mixture = 10 L
Alcohol =10% of mixture = 10% of 10 = 1 L.
Water = 9 L.
Let x Alcohol added. Now, Alcohol and Water ratio will be,
(1 + x)/9 = 12.5/87.5
1 +x = 12.5*9/87.5
1 + x = 112.5/87.5
1+ x = 1.2857
x = 1.2857 - 1
x = 0.286 L.
Alcohol added = 0.286 L.

Answer 2

The  volume of alcohol  to be added  is  1.25 litre.

Step-by-step explanation:

Given:

10 litre solution of water and alcohol contains 10% alcohol.

To be made 20% alcohol solution.

To Find :

The  alcohol  volume which is to be added .

Solution:

As given -10 litre solution of water and alcohol contains 10% alcohol.

Alcohol and water mixture = 10 litre

10% of alcohol  is =  1 litre

It means 90% is water = 9 litre

As given - To be made 20% alcohol solution.

Let P litre alcohol is to be added in 1 litre alcohol.

To be made 20% alcohol solution.

To be made solution  will contain  water $= (100\%-20\%) =80\%$

Now   P litre alcohol is to be added in 1 litre alcohol.

Alcohol and  water ratio can be written as below.

$\frac{(1+P)}{9} =\frac{20}{80}$

$\frac{(1+P)}{9} =\frac{1}{4}$

$4+4P=9$

$4P=5$

$P=1.25$

Thus, volume of alcohol    to be added  is  1.25 litre.