Answer:
E) -2.50 ; inferior
Explanation:
Before you earned $3,500 per month, you consumed 7 units per month. That means that you consumed 1 unit every $500 earned.
When your income increased to $4,000, you only consumed 5 units per month. That means that your consumption decreased to 1 unit for every $800.
The income elasticity of demand using the midpoint method is calculated by using the following formula:
income elasticity = {change in quantity demanded / [(old quantity + new quantity) / 2]} / {change in income / [(old income + new income) / 2]}
= {-2 / [(7 + 5) / 2]} / {500 / [(3,500 + 4,000) / 2]} = (-2 / 6) / (500 / 3,750) = -0.333 / 0.133 = -2.5
Since the income elasticity of demand is negative, the good X is an inferior good.
