GMAT数学统计类术语总结
<p> <span word="GMAT">GMAT</span>数学概念之统计</p><p> 1.平均数</p><p> 2.中数</p><p> <span word="To">To</span> <span word="calculate">calculate</span> <span word="the">the</span> <span word="median">median</span> <span word="of">of</span> <span word="n">n</span> <span word="numbers">numbers</span>，<span word="first">first</span> <span word="order">order</span> <span word="the">the</span> <span word="numbers">numbers</span> <span word="from">from</span> <span word="least">least</span> <span word="to">to</span> <span word="greatest">greatest</span>;<span word="if">if</span> <span word="n">n</span> <span word="is">is</span> <span word="odd">odd</span>，<span word="the">the</span> <span word="median">median</span> <span word="is">is</span> <span word="defined">defined</span> <span word="as">as</span> <span word="the">the</span> <span word="middle">middle</span> <span word="number">number</span>，<span word="while">while</span> <span word="if">if</span> <span word="n">n</span> <span word="is">is</span> <span word="even">even</span>，<span word="the">the</span> <span word="median">median</span> <span word="is">is</span> <span word="defined">defined</span> <span word="as">as</span> <span word="the">the</span> <span word="average">average</span> <span word="of">of</span> <span word="the">the</span> <span word="two">two</span> <span word="middle">middle</span> <span word="numbers">numbers</span>. <span word="For">For</span> <span word="the">the</span> <span word="data">data</span> 6, 4, 7, 10, 4, <span word="the">the</span> <span word="numbers">numbers</span>, <span word="in">in</span> <span word="order">order</span>, <span word="are">are</span> 4, 4, 6, 7, 10, <span word="and">and</span> <span word="the">the</span> <span word="median">median</span> <span word="is">is</span> 6, <span word="the">the</span> <span word="middle">middle</span> <span word="number">number</span>. <span word="For">For</span> <span word="the">the</span> <span word="numbers">numbers</span> 4, 6, 6, 8, 9, 12, <span word="the">the</span> <span word="median">median</span> <span word="is">is</span> /2 = 7. <span word="Note">Note</span> <span word="that">that</span> <span word="the">the</span> <span word="mean">mean</span> <span word="of">of</span> <span word="these">these</span> <span word="numbers">numbers</span> <span word="is">is</span> 7.5.</p><p> 3.众数：一组数中的众数是指出现频率最高的数。</p><p> 例：<span word="the">the</span> <span word="mode">mode</span> <span word="of">of</span> 7，9，6，7，2，1 <span word="is">is</span> 7。</p><p> 4.值域：表明数的分布的量，其被定义为最大值减最小值的差。</p><p> 例：<span word="the">the</span> <span word="range">range</span> <span word="of">of</span>1，7，27，27，36 <span word="is">is</span> 36-= 37。</p><p> 5.标准方差：</p><p> <span word="One">One</span> <span word="of">of</span> <span word="the">the</span> <span word="most">most</span> <span word="common">common</span> <span word="measures">measures</span> <span word="of">of</span> <span word="dispersion">dispersion</span> <span word="is">is</span> <span word="the">the</span> <span word="standard">standard</span> <span word="deviation">deviation</span>. <span word="Generally">Generally</span> <span word="speaking">speaking</span>, <span word="the">the</span> <span word="greater">greater</span> <span word="the">the</span> <span word="data">data</span> <span word="are">are</span> <span word="spread">spread</span> <span word="away">away</span> <span word="from">from</span> <span word="the">the</span> <span word="mean">mean</span>, <span word="the">the</span> <span word="greater">greater</span> <span word="the">the</span> <span word="standard">standard</span> <span word="deviation">deviation</span>. <span word="The">The</span> <span word="standard">standard</span> <span word="deviation">deviation</span> <span word="of">of</span> <span word="n">n</span> <span word="numbers">numbers</span> <span word="can">can</span> <span word="be">be</span> <span word="calculated">calculated</span> <span word="as">as</span> <span word="follows">follows</span>:</p><p> <span word="find">find</span> <span word="the">the</span> <span word="arithmetic">arithmetic</span> <span word="mean">mean</span> ;</p><p> <span word="find">find</span> <span word="the">the</span> <span word="differences">differences</span> <span word="between">between</span> <span word="the">the</span> <span word="mean">mean</span> <span word="and">and</span> <span word="each">each</span> <span word="of">of</span> <span word="the">the</span> <span word="n">n</span> <span word="numbers">numbers</span> ;</p><p> <span word="square">square</span> <span word="each">each</span> <span word="of">of</span> <span word="the">the</span> <span word="differences">differences</span> ;</p><p> <span word="find">find</span> <span word="the">the</span> <span word="average">average</span> <span word="of">of</span> <span word="the">the</span> <span word="squared">squared</span> <span word="differences">differences</span> ;</p><p> <span word="take">take</span> <span word="the">the</span> <span word="nonnegative">nonnegative</span> <span word="square">square</span> <span word="root">root</span> <span word="of">of</span> <span word="this">this</span> <span word="average">average</span>.</p>
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