Geographical Skills

Paper 2 calculations are usually straightforward but require correct method, units and sensible rounding. Candidates should show working because partial credit may be available and because it reduces avoidable errors.

Population density

Population density equals population divided by area. If a district has 2,400,000 people and an area of 12,000 square kilometres, density is 200 people per square kilometre. Ensure both values refer to the same area and year.

Density is an average and does not show internal concentration.

Absolute and percentage change

Absolute change equals new value minus old value. Percentage change equals change divided by the old value, multiplied by 100. If exports rise from 50 to 65 units, absolute increase is 15 and percentage increase is 30 percent.

Use the original value as the denominator unless the question specifies otherwise.

Ratios, proportions and averages

A ratio compares quantities and may be simplified by dividing both terms by the same number. A proportion is a fraction of a total. The arithmetic mean equals the sum of values divided by the number of values.

Check whether a weighted average is required; a simple average of provincial rates may not equal the national rate if populations differ.

Units and checking

Write km, km2, people per km2, percent or the relevant monetary unit. Round only at the end and follow any instruction on decimal places. Estimate the expected size before calculating; a density of 0.002 people per km2 for a major city signals a unit error.

In multi-step calculations, keep extra digits until the final answer.