If a pond contained 40 lotus plants in 2024, and through reproduction 8 new plants were added, so the population became 48 in the year 2025. Find out the correct birth rate.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 0.2 offspring per lotus per year
Birth rate is the number of new individuals born in a given time, divided by the number of individuals in the population at the start. It is a per capita rate, so it is counted per member of the starting population.
\( \displaystyle \text{Birth rate} = \frac{\text{number of new plants}}{\text{starting population}} \)
The starting population in 2024 is 40, and 8 new plants were added.
\( \displaystyle \text{Birth rate} = \frac{8}{40} = 0.2 \)
So the birth rate is 0.2 offspring per lotus per year. The figure of 48 plants is the new total. It is not used for the birth rate.
NCERT Extract:
Population Attributes – …
