Page 29 - Health, Population and Environment Education 10

CDR = 9.2
Rate of Natural Increase (RNI) = ?
We know,
CBR – CDR
RNI = × 100
1000
32.7 – 9.2
=
10
23.5
=
10
= 2.35%
∴ RNI of that country is 2.35%.

b. Population Growth Rate (PGR)
Population growth rate is the sum of rate of natural increase (RNI) and net migration rate
(NMR). It shows the increase or decrease of population in a place or a country.
Mathematically,
CBR + CDR + NMR
PGR = × 100
1000
It is expressed in percentage.

While calculating PGR, if the value of NMR is positive, ‘+’ sign is used but if the value of
NMR is negative, ‘–’ sign is used.

Worked out example: 13
If a place has 31 crude birth rate, 9 crude death rate and 2 migration rate, find out the
population growth rate of that place.

Solution:
Given,
In a place,
Crude Birth Rate (CBR) = 31
Crude Death Rate (CDR) = 9
Net Migration Rate (NMR) = 2
Population Growth Rate (PGR) = ?
We know,
CBR – CDR + NMR
PGR = × 100
1000
31 – 9 + 2
=
10
GREEN Health, Population and Environment Education Book-10 29