如果檸檬汁價格下降20%對橙汁需求有甚麼正面影響?

The eleasticity of demand for orange juice is elastic. That means the change in the quantity demand is greater than the change in price of orange juice.
When the lemon juice price is decreased by 20%, the demand for orange juice will decrease. It is because the lemon juice and orange juice are subsitute goods. Under the situation of decrease in demand of orange juice, the decrease of equilibrium quantity is greater than 20% because of the elastic demand of orange juice.

This question want you to know the relationship between lemon juice and orange juice that they are subsitute. When one demand is increase, the other one will decrease.

Assumed that the orange juice is a substitute of the lemon tea. The decrease in P of lemon tea will lead to decrease in demand for its substitute (orange juice). The demand curve of orange juice will shift upward. The P and Qe (Quantity transacted) will then be decrease as the this moment. As the price elascticity of orange juice is elastic, the change in Qe will be greater than 20% and the total revenue frome ornage juice will decrease.

唔駛講禁多
要假設檸檬汁同橙汁係代替品
檸檬汁價格下降,檸檬汁需求數量上升
由於一樣貨品買多了,另一樣代替品會買少d
言則對橙汁需求下降,橙汁需求曲線向下移
橙汁需求數量下降,總收入下降,其他因素不變