Ramesh prepares solutions of alcohol in water according to customers 39 needs This morning Ramesh ha...........

Quantitative Aptitude (CDS) Mixture and Alligation

Ramesh prepares solutions of alcohol in water according to customers' needs. This morning Ramesh has prepared 30 liter of a 15% alcohol solution and kept it ready in a 30 liter delivery container to be shipped to the customer. Just before delivery, he finds out that the customer had asked for 30 liters of 20% alcohol solution. To prepare what the customer wants, Ramesh replaces a portion of 15% solution by 40% solution. How many liters of 15% solution are replaced?

5 liters

9 liters

10 liters

30 liters

Explanation:

Let Ramesh replaces x liters of 15% sol. with a 40% solution.
Now, quantity of 15% sol. in 30 liter = 30 × 15 / 100
Thus, After replacing we have a volume of 15% sol.
= ( 30× 15 / 100 - 15x/100 + 20x/100 )
= ( 450 + 5x ) / 100
This will be equal to 30 liter of 20% sol.
Therefore , ( 450 + 5x ) / 100 = 30× 20 / 100
450 + 5x = 600
Or 5x = 150
Or x = 30 liters