If 100 deaths take place in a population of 10,00,000 per year, then…

The correct answer is Option (2) → 0.0001 per person per year

The death rate of a population is the number of deaths per member of the population in a given time.

• Death rate = number of deaths ÷ size of the population

• = 100 ÷ 10,00,000

• = 0.0001 per person per year

Option (1) 0.001 per person per year — Incorrect. This would need 1000 deaths in the same population.

Option (3) 0.1 per person per year — Incorrect. This would need 1,00,000 deaths, one person in ten.

Option (4) 1 per person per year — Incorrect. This would mean every person died in the year.

NCERT Extract:
Population Attributes – “… An individual may have births and deaths, but a population has birth rates and death rates. In a population these rates refer to per capita births and deaths. The rates, hence, expressed are change in numbers (increase or decrease) with respect to members of the population. Here is an example. If in a pond there were 20 lotus plants last year and through reproduction 8 new plants are added, taking the current population to 28, we calculate the birth rate as 8/20 = 0.4 offspring per lotus per year. If 4 individuals in a laboratory population of 40 fruitflies died during a specified time interval, say a week, the death rate in the population during that period is 4/40 = 0.1 individuals per fruitfly per week.”