In a country, the number of births in a year for every 1000 people (the birth rate) and the number…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
In a country, the number of births in a year for every people (the birth rate) and the number of deaths for every people (the death rate) were measured twice. In 1950, the birth rate was and the death rate was . In 2000, the birth rate was and the death rate was .
- What was the yearly growth rate in 1950, in per cent?
- What was it in 2000, in per cent?
- The birth rate fell. Why did the growth rate still rise?
Need a reminder? The key ideaShow
A population that grows by per cent a year is multiplied by every year. After years: . The doubling time is , close to years. The growth in a year, per people, is the birth rate minus the death rate.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. 1950: birth rate , death rate . 2000: birth rate , death rate , all for every people.
Plan. Subtract the death rate from the birth rate. Change the answer to a per cent.
Step 1. 1950. for every , which is a year.
Step 2. 2000. for every , which is a year.
Step 3. The reason. The birth rate fell by , but the death rate fell by . So the gap between them became wider.
Answer: ; ; the death rate fell more than the birth rate.
Check. This is the pattern that NCERT describes for India: a fall in the death rate and in the maternal and infant mortality rates.
Watch out. A fall in the birth rate alone does not make the growth rate fall, if the death rate falls even more. The numbers here are made up to show the idea.
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