今年的植树节,我校栽的树苗成活了385棵,15棵没有成活,这批树苗成活率是多少

解题思路：根据均数，中位数，众数，方差的意义对各选项依次分析，即可得出正确答案．

A、平均数是5，（4+6+5+6+4+o+6+6）÷8=5，正确；
B、众数是6，6出现4次，最o，正确；
C、中位数是5，（6+5）÷2=5.5，故本选项错误；
1、方差是1.25，正确．
故选C．

点评：
本题考点： 方差；算术平均数；中位数；众数．

考点点评： 本题考查了平均数，中位数，众数，方差的意义．平均数平均数表示一组数据的平均程度．中位数是将一组数据从小到大（或从大到小）重新排列后，最中间的那个数（或最中间两个数的平均数）；一组数据中出现次数最多的数据叫做众数．方差是用来衡量一组数据波动大小的量．

松树棵数为124/4=31棵.
杨树的棵数为31*2+23=85棵.
.

成活率
=（80-4）÷80*100%
=76÷80*100%
=0.95*100%
=95%
准错不了

Tree
As everybody knows,wood has many uses．It is a kind of very important building material．Wood can be made into desks,chairs,beds and many other things．Fine paper is made of wood,too．Only trees can provide us with enough wood．Trees can also provide us with oxygen and make the air around us fresh．In hot summer trees give us shade and make our surroundings more beautiful．What’s more,trees can stop soil from being washed away by heavy rains．Since trees are so important to us,we should plant more trees．At the same time,many effective measures should be taken to protect forests and prevent trees from being cut down．
备注：选自初中优秀英语习作（略有改动）.

一班51棵
二班17棵
三班32棵