Question 19

Explanation

Given:

• Initial ratio of alcohol : water = $4 : 3$
• Added $5$ liters of water
• Final ratio of alcohol : water = $4 : 5$

Analyzing Ratio Changes

Since only water is added, the amount of alcohol remains constant. Let's look at the alcohol ratio parts:

• Initial: $4$ parts
• Final: $4$ parts

Since the alcohol parts are already equal ($4$), we can directly compare the water parts.

Calculating Current Water Volume

Change in water parts:

• Initial: $3$ parts
• Final: $5$ parts
• Difference: $5 - 3 = 2$ parts

This difference of $2$ parts corresponds to the addition of $5$ liters of water.

So, the value per part is:

The current volume of water ($5$ parts) is:

Therefore, the amount of water currently contained in the solution is $12.5$ liters.