Population distribution and density

Population distribution and density
Population distribution means the pattern of where people live. World population distribution is uneven. Places which are sparsely populated contain few people. Places which are densely populated contain many people. Sparsely populated places tend to be difficult places to live. There are several natural and human factors that affect favoured conditions:

fertile valleys
a regular suply of water
a climate which is not too extreme
good communications
stable governments
good job opportunitiesAreas of high population density tend to be located between 20° and 60°N. This area contains a large land area and a relatively temperate climate.
Population density is a measurement of the number of people in an area. It is an average number. Population density is calculated by dividing the number of people by area. Population density is usually shown as the number of people per square kilometer. As you can see in the following map there are densely populated areas and desertical areas:

TASKS: 1. Explain the world's population evolution in your own words. 2. What is the Demographic Transition Model? Explain it. 3. Which are the most populated areas of the world?, and the less populated areas? Why do you think have we this situation? 4. Calculate the population density of the following countries:  Country  Extension (km2)  Population  Population density (hab/km2)  Russian Federation  17 075.200  144 978.573    Canada  9 976.140  31 902.268    China  9 596.960  1.284 303.705    USA  9 629.091  280 562.484    Brazil  8 511.965  176 029.560    Australia  7 686.850  19 546.792    Chad  1 284.000  8 977.237    Japan  337.835  126 974.680   5. Do you think overpopulation is a problem?, why? What kind of measures are needed to face it? Sources: http://www.deathreference.com/Nu-Pu/Population-Growth.html http://www.globalchange.umich.edu/globalchange2/current/lectures/human_pop/human_pop.html#Past http://www.geography.learnontheinternet.co.uk/topics/popn1.html#factors