How much water should you add to 40 liters of 80% alcohol solution to get 70% alcohol?

We find the volume of alcohol in 40 liters of solution.

We multiply the volume of the solution by the percentage of alcohol content.

We get:

40 * 80% / 100% = 40 * 0.8 = 32 liters of alcohol.

Since this volume of alcohol should correspond to 70% in the new solution, we find the volume of the new solution.

Divide 32 liters of alcohol by 70%.

Will be:

32/70% = 32 / 0.7 = 45.71 liters.

From this it follows that it is necessary to add to the initial solution:

45.71 – 40 = 5.71 liters of water.

Answer: You need to add 5.71 liters.

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