JAMB Mathematics 2018 Paper

Concept:A pie chart represents parts of a whole using angles around a point, so the total angle is $360^\circ$.Each sector angle is proportional to the amount spent on that item.Explanation:Let the angle for school fees be $x^\circ$.Housing is twice school fees, so the housing angle is $2x^\circ$.The other two sectors in the chart have angles $120^\circ$ and $90^\circ$.The sum of all sector angles in a pie chart is $360^\circ$.Therefore:$$120^\circ + 90^\circ + x^\circ + 2x^\circ = 360^\circ$$Simplify:$$210^\circ + 3x^\circ = 360^\circ$$$$3x^\circ = 150^\circ$$$$x^\circ = 50^\circ$$Thus, housing angle $= 2x^\circ = 100^\circ$.Monthly income is N7200, so the housing expenditure is:$$\frac{100}{360} \times 7200 = 2000$$The worker spends N2000 on housing.Answer:B. N2000