2. what is the ratio of the average ( arithmetic mean)height of students in class X to the average height of students in class y?
(1) the average height of the students in class x is 120 centimeters
(2) the average height of the students in class x and class y combined is 126 centimeters.
why not c?
平均的算法是什么啊???
应该是:总身高/人数 啊。你现在没有人数就求不出来总身高和人数,所以不可以做。E
给你举个最简单的例子:4个人考试,平均15分;另外10个人考试,平均8分;这14个人一起的平均是10分。
我猜你上面那个题想这么做:126×2-120=y对吧??那你做这个题就是:10×2-15=5对吧?而不是8
因为你错在默认X,Y班人数相等了。
概念问题,如果你不是粗心的话,那还是再看遍概念吧!!!
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