# QA – Placement Quizzes | Mixtures and Alligation | Question 13

A drum filled with a mixture of two liquids l1 and l2 in the ratio 5:7. When 9 liters of mixture is taken out and the replaced by l1. Now the ratio of l1 and l2 is 9:7. How many liters of the liquid l1 were there in the drum initially?

**(A)** 15

**(B)** 20

**(C)** 18

**(D)** 25

**Answer:** **(A)** **Explanation:** Let the initial quantity of l1 in the container be 5x.

Let the initial quantity of l2 in the container be 7x.

Now, 9 liters of mixture is drawn off from the container.

Quantity of l1 in 9 liters of the mixture drawn off

=9*5/12=15/4

Quantity of l2 in 9 liters of the mixture drawn off

=9*7/12=21/4

Hence,

Quantity of l1 remaining in the mixture after 9 liters is drawn off

=5x−15/4

Quantity of l2 remaining in the mixture after 9 liters is drawn off

=7x−21/4

Since the container is filled with l1 after 9 liters of mixture is drawn off, quantity of l1 in the mixture

=5x-15/4+9=5x+21/4.

Given that the ratio of l1 and l2 becomes 9:7

⇒5x+21/4:7x-21/4=9:7

⇒20x+21:28x-21=9:7

⇒7(20x+21)=9(28x-21)

⇒140x+147=252x-189

⇒112x=336

⇒x=3.

Therefore, liters of l1 present in the container initially

=5x=(5*3)=15.

Quiz of this Question

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