JAMB Economics 2014 Paper

Concept:In a pie chart, each sector's angle is proportional to its contribution, so the percentage contribution is the sector angle divided by the total angle of $360^\circ$, multiplied by $100$.Explanation:From the pie chart, the other sectors have angles $126^\circ$, $72^\circ$, and $108^\circ$.Their sum is $126^\circ + 72^\circ + 108^\circ = 306^\circ$.Since a full circle is $360^\circ$, the services sector angle is $360^\circ - 306^\circ = 54^\circ$.Thus, the percentage contribution of services is $\frac{54^\circ}{360^\circ} \times 100 = 15\%$.This means services contribute $15\%$ of the national income.Answer:A. $15\%$