Question

How many liters of a 25% saline solution must beadded to 3 liters of a 10% saline solution to obtain a15% saline solution?

Answer 1

Let x liters of 25% saline Is added to the 3 liters of 10% saline
X(25/100)+3(10/100)=(x+3)15/100
X=1.5 liters

Answer 2

Given :

25% of saline solution is added to 3 liters of 10% saline solution

The resultant solution = 15% of saline solution

To find :

The quantity of 25% saline solution

Solution :

Let The quantity of 25% saline solution = x liters

The quantity of 10% saline solution = 3 liters

The quantity of 15% saline solution = ( x + 3 ) liters

So, According to question

 25% of x + 10% of 3 + 15% of ( x + 3 )

Or,  $\dfrac{25}{100}$ × x + $\dfrac{10}{100}$ × 3 = $\dfrac{15}{100}$ × ( x + 3 )

Or,  25 x + 30 = 15 ( x + 3 )

Or,  25 x + 30 = 15 x + 45

Or,  25 x - 15 x = 45 - 30

Or,             10 x = 15

∴                    x = $\dfrac{15}{10}$

i.e                  x = 1.5 liters

So, The quantity of 25% saline solution = x = 1.5 liters

Hence, The quantity of 25% saline solution is 1.5 liters  Answer