问题
单项选择题
If the admission price for a rock concert is raised from $25 to $30, causing ticket sales to drop from 60000 to 40000, the price elasticity of demand for tickets is:（）
A. -0.25.
B. -0.50.
C. -2.20.
答案
参考答案：C
解析：
Price elasticity = (percentage change in quantity)/( percentage change in price). Use average value in calculating the percentage change in quantity and price. (-20/50)/(5/27.50)=-0.4/0.1818=-2.20