If the price of biscuit per packet increased from N250 to N500 and the quantity bought per week decreased from 300 to 200 packets, determine the elasticity of demand for biscuit.

The the elasticity of demand for biscuit is -0.33.

Explanation:

Elasticity demand is the degree of responsiveness of quantity demanded for a commodity to a change in the price of that commodity.

The elasticity of demand for biscuit can be calculated using the following elasticity of demand formula:

Elasticity of demand =  Percentage change in Qd / Percentage change in price (1)

Where Qd denotes quantity demanded.

Percentage change in Qd = [(New Quantity - Old Quantity) / Old quantity] * 100 = [(200 - 300) / 300] * 100 = -33.33%

Percentage change in price = [(New price - Old price) / Old price] * 100 = [(N500 - N250) / N250] * 100 = 100%

Substituting the values into equation (1), we have:

Elasticity of demand = -33.33% / 100% = - 0.33

Therefore, the the elasticity of demand for biscuit is -0.33.

Note that since -0.33 in absolute term |-0.33| is less than 1, the demand for biscuit is inelastic. That is, the change in the quantity demanded for biscuit responds less than the change in its price.