How many liters of water do you need to add to 20 liters of a 10% solution to get a 5% solution?

To solve the problem, you first need to determine the weight of the solution, which is contained in 20 liters of water.

To do this, multiply the initial weight of the water by the percentage.

We get:

20 * 10% / 100% = 20 * 0.1 = 2 kg of solution.

We find how much water should be.

To do this, we divide the known weight of the solution by the new percentage.

2/5% = 2 / 0.05 = 40 liters of water.

Find how many liters of water you need to add.

To do this, subtract 20 from 40 liters.

We get:

40 – 20 = 20 liters.

Answer: you need to add 20 liters of water.