NCERT says that the population of India was about 350 million at independence in 1947, and that it…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
NCERT says that the population of India was about million at independence in 1947, and that it crossed billion, that is million, in 2011. Treat the growth between the two years as a steady growth by the same share every year.
- How many times larger was the population in 2011 than in 1947?
- What was the yearly growth rate, in per cent?
- At that rate, how long does the population take to double?
- Is the rate above or below per cent a year?
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. million in 1947. million in 2011. Time years.
Plan. Find the ratio, take the root for the yearly factor, and use the doubling formula.
Step 1. The ratio. times.
Step 2. The yearly factor. , so . The growth rate is a year.
Step 3. The doubling time. years.
Step 4. Compare. is below a year.
Answer: times; a year; years; below .
Check. The rule of 70 gives years, which agrees.
Watch out. A steady rate is a model. The real rate was higher at some times and lower at others.
Source. NCERT (2023), Biology Class XII, chapter 3, for the two populations.
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