# Population and Urbanization

Business I · Sociology · https://tryals.app/learn/business-i/population-and-urbanization

## Counting Humanity

Demography is sociology with real data: births, deaths, and moves remaking markets decades in advance.

**Core rates** (per 1,000 people/year) include the **crude birth rate**, **crude death rate**, and **natural increase** (their difference). Add net migration for total growth:

$$\text{growth} = \frac{\text{births} - \text{deaths}}{1000} + \text{net migration}$$

A population growing at $g\%$ doubles in roughly $70/g$ years, applying the **Rule of 70** to human numbers.

**Population pyramids** photograph age structures: a wide triangle means Stage 2 youth explosions, while a barrel shape means aging Stage 4 societies.

## The Demographic Transition

| Stage | Births | Deaths | Population |
| --- | --- | --- | --- |
| **1. Pre-industrial** | High | High | Barely grows |
| **2. Early transition** | High | Falling | Explodes |
| **3. Late transition** | Falling | Low | Growth slows |
| **4. Post-transition** | Low | Low | Stabilizes |

**Urbanization** accompanies this shift, concentrating labor and driving Durkheim's move from **mechanical solidarity** (likeness) to **organic solidarity** (interdependence).

> **Pitfall:** Fertility drops do not instantly halt growth. **Demographic momentum** keeps young populations growing for decades because large cohorts have not yet had children.

## Practice questions

6 of this lesson's 14 practice questions, with answers. The full set is in the app.

### 1. Durkheim argued that cities replace the village’s solidarity of likeness with a solidarity based on the interdependence of specialists.

**Answer:** True

**Why:** Mechanical solidarity (we cohere because we are alike) gives way to organic solidarity (we cohere because we need each other’s different work). A city, or a firm’s org chart, is organic solidarity drawn as a map.

Page: https://tryals.app/practice/business-i/population-and-urbanization/durkheim-argued-that-cities-replace-the-villages-solidarity-of

### 2. Which force pushes births _down_ during the transition, and which pushed deaths down first? Sort the drivers.

**Answer:**

- Lowered death rates: Clean water and sewage systems, Vaccination campaigns
- Lowered birth rates: Mass female education, Urban living raising the cost of children, Access to contraception

**Why:** Deaths fall from public-health engineering; births fall from social change, which is why the two curves fall decades apart, and the gap between them is the population explosion.

Page: https://tryals.app/practice/business-i/population-and-urbanization/which-force-pushes-births-down-during-the-transition-and-which

### 3. Match each pyramid shape to its demographic meaning.

**Answer:**

- Wide-based triangle → Young, fast-growing population (stage 2)
- Barrel / column → Stable, aging population (stage 4)
- Inverted base (narrow bottom) → Shrinking birth cohorts
- Bulge in middle ages → A baby boom moving through time

**Why:** A pyramid is a time machine: each band is a birth cohort marching upward at one year per year. Today’s bulge is 2050’s pension bill, already visible.

Page: https://tryals.app/practice/business-i/population-and-urbanization/match-each-pyramid-shape-to-its-demographic-meaning

### 4. A country's fertility rate falls below replacement today, and its population keeps growing for another thirty years. What explains the lag?

A. Immigration, which offsets the falling birth rate
B. Falling death rates, which cancel the effect of lower fertility
C. Measurement lag, since fertility statistics are published years after the fact
D. Population momentum, from a large cohort of childbearing age

**Answer:** D. Population momentum, from a large cohort of childbearing age

**Why:** A rate below replacement multiplied by an unusually large parent cohort still yields more births than deaths, and the structure takes a generation to work through. This is why demographic forecasts are unusually reliable, the people who will be forty in forty years are already born.

Page: https://tryals.app/practice/business-i/population-and-urbanization/a-countrys-fertility-rate-falls-below-replacement-today-and-its

### 5. A country has a birth rate of 22 and a death rate of 8 per 1,000, and net migration adds 2 per 1,000. Compute its total growth rate **as a percentage**.

**Answer:** 1.6 (within ±0.05)

**Why:** $(22 - 8 + 2) / 1000 = 16 / 1000 = 1.6\%$ a year. Rule of 70: doubling in about 44 years, the kind of number housing planners need before the babies are born.

Page: https://tryals.app/practice/business-i/population-and-urbanization/a-country-has-a-birth-rate-of-22-and-a-death-rate-of-8-per-1-000-and

### 6. Order the demographic transition’s stages by what falls when.

**Answer:**

1. High births and high deaths hold population flat
2. Sanitation and vaccines pull the death rate down
3. The gap between the rates explodes the population
4. Education and urban life pull the birth rate down
5. Both rates low: growth stalls and the society ages

**Why:** Deaths fall first, births fall late, and everything dramatic in modern demography happens in the lag between them.

Page: https://tryals.app/practice/business-i/population-and-urbanization/order-the-demographic-transitions-stages-by-what-falls-when