# Word Problems 7

**Problem 7: The percentage of water in 20 litters of adulterated milk is 10. The quantity of water to be added to it to increase the percentage of water to 25 is ;**

**a) 4 litters b) 5 litters c) 7 litters d) 8 litters**

**Solution: **

We are given that in 20 liters mixture of milk and water there is 10 percent water.

i-e Water = 10 % of 20 liter

or

So water in 20 liter mixture is 2 liters .

Now suppose if we add ‘y’ liters of more water { then total water will become y+2} and water percentage becomes 25 % of mixture {which will be y+20 now}

In other words we supposing that ;

or

Simplifying and shifting ‘y’ terms on one side;

So, we will have to add 4 more liters to make water concentration 25 % of 20+4=24 liters of mixture

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