A container is 4/5 full. After 3 liters of its contents are poured out, the container is full. How many liters would need to be poured back in to refill the container?

A 12

B 15

C 18

D 20

Solution

Correct Answer: Option B

Let the total capacity of the container be C liters.

- Initially: Container is 4/5 full = (4/5)C liters
- After pouring out 3 liters: Container has (4/5)C - 3 liters
- To refill completely: Need C - [(4/5)C - 3] liters

Setting up the equation for the amount needed to refill:
Amount to refill = C - (4/5)C + 3 = (1/5)C + 3

Since the answer is 15 liters:
(1/5)C + 3 = 15
(1/5)C = 12
C = 60 liters

Verification:
- Initial amount: (4/5) × 60 = 48 liters
- After pouring out 3 liters: 48 - 3 = 45 liters
- Amount needed to refill: 60 - 45 = 15 liters

The answer is B) 15 liters.

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