The answer is
60% rise in quantity demanded of good x.
Explanation:
Percentage change in quantity demanded for good Y:
= (Change in Quantity ÷ Initial Quantity) × 100
= (60 units ÷ 400 units) × 100
= 15%
Percentage change in price of good Y = 10% Rise
Therefore, the price elasticity of demand for Good Y is as follows:
= Percentage change in Quantity demanded ÷ Percentage change in price
= 15 ÷ 10
= 1.5
Hence,
Price elasticity of demand of good x:
= 2 × price elasticity of demand of good y
= 2 × 1.5
= 3
Percentage change in price of good x:
= (Change in price ÷ Initial price) × 100
= (2 ÷ 10) × 100
= 20%
Therefore,
Price elasticity of demand for Good x = Percentage change in Quantity demanded ÷ Percentage change in price
3 = Percentage change in Quantity demanded ÷ 20
3 × 20 = Percentage change in Quantity demanded
60% = Percentage change in Quantity demanded for good x
Hence, 60% rise in quantity demanded of good x.