全面提分从解决每个单项的薄弱点开始，锁定问题，各个击破。
主旨题和细节题哪个是薄弱点
逻辑推理条件是否充分
选项都没有语法错误选哪个
数学多考1分，语文可以少考3分
练熟题型思考步骤，充分条件准确判断
IR考出8分点亮成绩单
题不在多，吃透就行。知其然且知其所以然，就能经得住考场挑战。
不扯淡，只讲题
每个人都曾经是一只小白，考GMAT你需要知道的事情都在这里。
名师逐题讲解，即点即听；提出问题当天解答，实时推送至微信；不废话，只讲题！
Economist: In 2015, the average per-person amount paid for goods and services purchased by consumers in Country X was the equivalent of $17,570 in United States dollars, just 30 percent of the corresponding figure of $58,566 for Country Y. Yet in 2015, there was already a substantial middle class in Country X that had discretionary income for middle-class consumer goods such as new vehicles, computers, or major household appliances, while a significant portion of the middle class in Country Y did not have sufficient income to purchase such items.
Which of the following, if true, most helps explain the discrepancy in the relationships described by the economist?
