问题
单项选择题
An analyst does research about the income elasticity of demand. As income rises from $500 per week to $1500 per week, the quantity demanded for a product increases from 1100 units to 1500 units. the income elasticity of demand is closest to:
A. 0.25
B. 0.31
C. 0.40
答案
参考答案：B
解析： [(1500-1100)/(1500+1100)/21/[($1500-$500)/($1500+$500)/2]=0.3077/1=0.3077。