In a mixture 25 liters, the ratio of milk and water is 4:1. How many liters of milk must be added to make the ratio 16:1? Options : 60 70 80 50

Sure, let's solve this step by step:

1. In the initial mixture of 25 liters, the ratio of milk to water is 4:1. This means that for every 4 parts of milk, there is 1 part of water.

2. To find out how many liters of milk and water are there in the mixture, we divide 25 by the total parts in the ratio. The total parts in the ratio are 4 (for milk) + 1 (for water) = 5 parts.

3. So, each part is equal to 25/5 = 5 liters.

4. Therefore, in the initial mixture, there are 4 parts of milk * 5 liters/part = 20 liters of milk and 1 part of water * 5 liters/part = 5 liters of water.

5. We want to add some milk to make the ratio 16:1. This means that for every 16 parts of milk, there is 1 part of water. But we know that the amount of water is not changing, it's still 5 liters.

6. So, in the new mixture, the 1 part (which is water) is equal to 5 liters. Therefore, 16 parts (which is milk) is equal to 16 * 5 = 80 liters.

7. Therefore, to achieve this new ratio, we need to add 80 liters (the total amount of milk in the new ratio) - 20 liters (the initial amount of milk) = 60 liters of milk.

So, the correct answer is 60 liters.