Multiple choice general knowledge math & puzzles

Madagascar Island, there are x dodos in a particular year. 30 dodos in a thousand of the original population die every year and 25 dodos in a thousand of the original population are born every year. In how many years will the population of dodos halve itself ?

  1. 200

  2. 125

  3. 100

  4. Indeterminate

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Net change is 25 - 30 = -5 per 1000, or -0.5% per year. To halve (50% reduction) via linear reduction of the original population: 50 / 0.5 = 100 years.