问题
单项选择题
If the price of a candy bar increases from $ 0.50 to $ 0.55 and the quantity demanded decreases from 267 to 235, the price elasticity of demand is:（）
A. -1.23.
B. 1.23.
C. -1.34
答案
参考答案：C
解析：
Price elasticity of demand is calculated by dividing the percent change in quantity demanded by the percent change in price, using the average value of the variable in the computations. The percent change in quantity demanded is (235-267)/[(235+267)/2]=-0.127 or -12.7%. The percent change in price is = (0.55-0.50)/[(0.55+0.50)/21=0.095 or 9.5%. The price elasticity of demand is -12.7/9.5=-1.34.