gmat数学疑问1、 in city x last April,was the average(arithmetic mean) daily high temperature greater than the median daily high temperature?(1) in city x last April,the sum of the 30 daily high temperature was 2,160°(2) in city x last April,60% of the daily high temperature were less than the average daily high temperature.题目中的60%没有说是最前面那几天啊?有可能是前九天和九天,那怎么可以估计到中位数呢?
问题描述：
gmat数学疑问
1、 in city x last April,was the average(arithmetic mean) daily high temperature greater than the median daily high temperature?
(1) in city x last April,the sum of the 30 daily high temperature was 2,160°
(2) in city x last April,60% of the daily high temperature were less than the average daily high temperature.
题目中的60%没有说是最前面那几天啊?有可能是前九天和九天,那怎么可以估计到中位数呢?
答
这题你是不是理不顺啊？ 我来给你详细推理一下。
设a为平均值，m为中位数。
根据题意：30天中60%的温度低于a，意思是一个月中有18天温度低于a，设这18天从大到小依次为X1，X2，X3.....X18(所有Xi都小于a)。
不难发现，X1为所有30天中温度最低的温度，而X15和X16的平均值等于m。 所以m小于a
答
gmat数学难度就在于 不读题目，你多看看单词，考的都是非常基本的内容。如果你感觉还是不懂的话就听听管卫东老师讲的gmat数学课吧！
答
中位数按数字大小排序,和天数顺序无关.所以2就可以了.