From a vessel containing pure milk, 20% is replaced by water and the process is repeated 2 more times. At the end of the third op…

Question

From a vessel containing pure milk, 20% is replaced by water and the process is repeated 2 more times. At the end of the third operation, the percentage of pure milk in the mixture is:

1. A. 40%
2. B. 51.2% (Correct answer)
3. C. 60%
4. D. 25%

Correct Answer

Option B — 51.2%

Detailed Solution & Explanation

The correct answer is 51.2%.

Key Points

• After each replacement of 20%, pure milk = 80% of previous.
• After 3 operations: 100 × (0.8)³ = 100 × 0.512 = 51.2%.

प्रश्न (हिन्दी में)

शुद्ध दूध वाले बर्तन से 20% दूध पानी से बदल दिया गया और यही प्रक्रिया दो बार और की गई। तीसरी प्रक्रिया के बाद शुद्ध दूध का प्रतिशत है:

1. A. 40%
2. B. 51.2%
3. C. 60%
4. D. 25%