Final answer:
To increase quantity demanded by 20% with an advertising elasticity of demand of 0.50, advertising spending needs to be increased by 40%.
Step-by-step explanation:
If you know that the advertising elasticity of demand for your product is 0.50 and you want to increase the quantity demanded by your customers by 20%, you can use the advertising elasticity of demand to determine by how much you need to increase your advertising spending. According to the definition of elasticity, a 1% increase in advertising spending would lead to a 0.5% increase in quantity demanded. Therefore, to achieve a 20% increase in quantity demanded, you would need to increase your advertising spending by 40%.