GRE数学难题总结(上)
<p> 1. <span word="n">n</span>个数从小到大排列,求/4,设商为<span word="i">i</span>,余数为<span word="j">j</span> ,则可求得1<span word="st">st</span> <span word="Quartile">Quartile</span>为:/4+<span word="j">j</span>/4</p><p> 2. 4个,2个的排列方式 15(=)</p><p> 3 .5双袜子,同时去2只,刚好配对的概率。1/9</p><p> 4. 40人说<span word="French">French</span>,60人说<span word="Russian">Russian</span>,80人说<span word="Italy">Italy</span>,说两种语言的有50人,说三种语言的有 10人. 共有125人,问不说这些语言的有几人. <span word="Key">Key</span>:125-=15</p><p> 5 .等腰直角三角形边长2加2倍根号2,求面积。</p><p> 6. 某种溶液浓度为125<span word="gram">gram</span> <span word="per">per</span> <span word="liter">liter</span>, 转换成 <span word="ounce">ounce</span> <span word="per">per</span> <span word="gallon">gallon</span>,求表达式.已知 1 <span word="ounce">ounce</span>=28.<span word="xxx">xxx</span> <span word="gram">gram</span> <span word="and">and</span> 1 <span word="gallon">gallon</span>=3.875 <span word="liter">liter</span></p><p> 7. <span word="x">x</span>,<span word="y">y</span>,<span word="z">z</span> 均方差为<span word="d">d</span>, 求<span word="x">x</span>+10,<span word="y">y</span>+10,<span word="z">z</span>+10的均方差 (<span word="d">d</span>)</p><p> 8. 1的概率是0.8,2的概率是0,6,问是1或是2或是<span word="both">both</span>的概率,1-0.60.8=0.92.</p><p> 9. 还有一组测量数据中,12.1比<span word="mean">mean</span>低1.5个标准差,17.5比<span word="mean">mean</span>高3.0个标准方差.问<span word="mean">mean</span>是多少.13.9(设标准差为X 12.1+1.5X=M,17.5-3X=M)</p><p> 10. 图表题,1992年总和是50,96年是60,每年至少增长1,问最大的年增长:7.0</p><p> 11 .<span word="x">x</span>+<span word="y">y</span>=52<span word="x">x</span>+2<span word="y">y</span>=8之间最短距离与1比较 1</p><p> 12. 以40<span word="miles">miles</span>/<span word="hour">hour</span>速度经过一1.5<span word="miles">miles</span>的路,若超速则罚款<span word="fine">fine</span>=50+(速度-40)10,现一人用108秒通过此路,问她的<span word="fine">fine</span>=? <span word="key">key</span> 150</p><p> 13. <span word="xyz">xyz</span> <span word="togather">togather</span> <span word="finish">finish</span> <span word="the">the</span> <span word="task">task</span> <span word="for">for</span> 9 <span word="hour">hour</span>, <span word="xy">xy</span> <span word="togather">togather</span> <span word="need">need</span> 12 <span word="hour">hour</span>,<span word="z">z</span> <span word="alone">alone</span> <span word="needs">needs</span> ? <span word="hour">hour</span>. <span word="key">key</span> 36</p>
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