Mathematics (Arithmetic)
Arithmetic here is school-level but timed, and the paper uses health-flavoured data - cases, population, coverage, doses - so unit sense matters as much as calculation speed.
Core areas
- Percentage and ratio-proportion - case counts, coverage, dilution of chlorine solutions.
- Average, simple and compound interest - pay, loans, growth of case numbers.
- Time, speed, distance and time-and-work - staff deployment and spray coverage.
- Mensuration and data interpretation - area of a ward, volume of a water tank, reading a table.
Useful unit facts: 1 cubic metre = 1000 litres, so a tank 2 m × 1 m × 0.5 m holds 1 m³ or 1000 litres.
Worked example
A block has a population of 2,400. In one month, 96 confirmed malaria cases were reported. Find the annual parasite incidence (API) per 1000 population, assuming this monthly figure represents the year's average month. Reasoning: API is expressed per 1000 people per year. Monthly rate per 1000 = (96 ÷ 2400) × 1000 = 40. Annualise: 40 × 12 = 480 per 1000 per year. Notice how the same numbers give 4 percent for the month - the percentage and the per-1000 rate are different statements, and the annual figure is twelve times the monthly rate.
Traps that cost marks
- Forgetting to annualise when a question says per year but gives monthly data.
- Mixing per-100 and per-1000 scaling.
- Using the total population when the question asks for a rate among a subgroup (children, households, workers).
- Ignoring the units in the options - litres against cubic metres, days against hours.