JAMB Economics 2014 Paper

Concept:At equilibrium, quantity demanded equals quantity supplied: $Q_d = Q_s$.The value of $P$ that makes these equal is the equilibrium price.Explanation:Set the demand function equal to the supply function.$40 - 2P = 6P + 24$.Collect the $P$ terms on one side and the constants on the other side.$40 - 24 = 6P + 2P$.Simplify both sides.$16 = 8P$.Divide both sides by $8$.$P = \frac{16}{8} = 2$.So the equilibrium price is $2$.Check by substituting $P = 2$ into both equations.$Q_d = 40 - 2(2) = 40 - 4 = 36$.$Q_s = 6(2) + 24 = 12 + 24 = 36$.The equilibrium quantity is therefore $36$.Answer:The equilibrium price is $2$, which is not listed among the options.Option C, $36$, is the equilibrium quantity, not the equilibrium price.