SME
Human Geography
Population and migration
Use this for “A city of 500,000 had 6,000 births, 4,000 deaths, 3,000 arrivals and 1,000 departures. How much did it grow?”
Chart
Natural increase: N = 2,000
Net migration: M = 2,000
Population change: ΔP = 4,000
This is an example. Type your own values to start a new problem.
ΔP
=
(
B
−
D
)
+
(
I
−
E
)
P₀
Population
example
N
Natural increase
calculated
M
Net migration
calculated
RNI
Rate of natural increase
calculated · %
Formulas
N
=
B
−
D
2,000 = 6,000 − 4,000
M
=
I
−
E
2,000 = 3,000 − 1,000
ΔP
=
N
+
M
4,000 = 2,000 + 2,000
RNI
=
N
P₀
×
100
0.4
=
2,000
500,000
×
100
Assumptions
•
Counts are for one place over one year; P₀ is the mid-year population.
•
Population changes only through births, deaths, and people moving in or out.
•
RNI is the natural increase as a percent of P₀; it leaves out migration.
Step-by-step
WE KNOW
P₀ = 500,000, B = 6,000, D = 4,000, I = 3,000, E = 1,000
FIND
natural increase (N), net migration (M), population change (ΔP), rate of natural increase (RNI)
Step 1 · Find natural increase (N)
Use N = B − D
Natural increase is births minus deaths.
N
=
6,000
−
4,000
N
=
2,000
Step 2 · Find net migration (M)
Use M = I − E
Net migration is people moving in minus people moving out.
M
=
3,000
−
1,000
M
=
2,000
Step 3 · Find population change (ΔP)
Use ΔP = N + M
Population change is natural increase plus net migration.
ΔP = 2,000 + 2,000
ΔP = 4,000
Step 4 · Find rate of natural increase (RNI)
Use RNI = N ÷ P₀ × 100
Natural increase as a percent of the population.
RNI
=
2,000
500,000
×
100
RNI = 0.004 × 100
RNI = 0.4%
Check
Put the numbers back in. Both sides should match.
2,000 = 6,000 − 4,000 ✓
2,000 = 3,000 − 1,000 ✓
4,000 = 2,000 + 2,000 ✓
0.4
=
2,000
500,000
×
100
✓
Topic check
See what you know: 5 questions on this topic
New questions each time. Pass to mark it complete.
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