Question:
The population of a city decreases by 15% in the first year, increases by 20% in the second year, and again decreases by 10% in the third year. If the population at the beginning was 50,000, what will it be after 3 years?
एक शहर की जनसंख्या पहले वर्ष 15% घटती है, दूसरे वर्ष 20% बढ़ती है और तीसरे वर्ष पुनः 10% घटती है। यदि प्रारंभ में जनसंख्या 50,000 थी, तो 3 वर्ष बाद यह कितनी होगी?
Options:
- 45,900
- 48,600
- 51,000
- 54,000
- 45,900
- 48,600
- 51,000
- 54,000
Correct Answer: a)
Explanation:
Population after 3 years \(= 50000 \times (1 – 0.15) \times (1 + 0.20) \times (1 – 0.10)\)
\(= 50000 \times 0.85 \times 1.20 \times 0.90 = 50000 \times 0.918 = 45,900\).
3 वर्ष बाद जनसंख्या \(= 50000 \times 0.85 \times 1.20 \times 0.90 = 50000 \times 0.918 = 45,900\)।