GRE数学知识有哪些难点
<p> 1.<span word="mode">mode</span></p><p> 一堆数中出现频率最高的一个或几个数</p><p> <span word="e">e</span>.<span word="g">g</span>. <span word="mode">mode</span> <span word="of">of</span> 1，1，1，2，3，0，0，0，5 <span word="is">is</span> 1 <span word="and">and</span> 0</p><p> 2.<span word="range">range</span></p><p> 一堆数中最大和最小数之差 ，所以统计学上又称之为极差</p><p> <span word="e">e</span>.<span word="g">g</span>. <span word="range">range</span> <span word="of">of</span> 1，1，2，3，5 <span word="is">is</span> 5-1=4</p><p> 3.<span word="mean">mean</span></p><p> <span word="arithmatic">arithmatic</span> <span word="mean">mean</span>： <span word="n">n</span>个数之和再除以<span word="n">n</span></p><p> <span word="geometric">geometric</span> <span word="mean">mean</span> ： <span word="n">n</span>个数之积的<span word="n">n</span>次方根</p><p> 4.<span word="median">median</span></p><p> 将一堆数排序之后，正中间的一个数，</p><p> 或者中间两个数的平均数</p><p> <span word="e">e</span>.<span word="g">g</span>. <span word="median">median</span> <span word="of">of</span> 1，7，4，9，2，2，2，2，2，5，8 <span word="is">is</span> 2</p><p> <span word="median">median</span> <span word="of">of</span> 1，7，4，9，2，5 <span word="is">is</span> /2=6</p><p> 5.<span word="standard">standard</span> <span word="error">error</span></p><p> 一堆数中，每个数与平均数的差的绝对值之和，除以这堆数的个数</p><p> <span word="e">e</span>.<span word="g">g</span>. <span word="standard">standard</span> <span word="error">error</span> <span word="of">of</span> 0，2，5，7，6 <span word="is">is</span>：</p><p> /5=2.4</p><p> 6.<span word="standard">standard</span> <span word="variation">variation</span></p><p> 一堆数中，每个数与平均数之差的平方之和，再除以<span word="n">n</span></p><p> 标准方差的公式：<span word="d">d</span>2=/<span word="n">n</span></p><p> <span word="e">e</span>.<span word="g">g</span>. <span word="standard">standard</span> <span word="variation">variation</span> <span word="of">of</span> 0，2，5，7，6 <span word="is">is</span>： <span word="average">average</span>=4</p><p> 2 +2+2+2+2)/5=6.8</p><p> 7.<span word="standard">standard</span> <span word="deviation">deviation</span> 标准偏差</p>
页:
[1]