GRE数学考试有哪些技巧
<p> 本文就概念法和画图法对新<span word="GRE">GRE</span>数学考试进行解析：</p><p> 学生总数240，学<span word="SCIENCE">SCIENCE</span>的是140，学<span word="MATH">MATH</span>的170，求<span word="LEARN">LEARN</span> <span word="MATH">MATH</span> <span word="BUT">BUT</span> <span word="NOT">NOT</span> <span word="SCIENCE">SCIENCE</span>的人数?</p><p> 1)<span word="THERE">THERE</span> <span word="ARE">ARE</span> 55 <span word="STUDENTS">STUDENTS</span> <span word="WHO">WHO</span> <span word="LEARN">LEARN</span> <span word="SCIENCE">SCIENCE</span> <span word="BUT">BUT</span> <span word="NOT">NOT</span> <span word="MATH">MATH</span></p><p> 2)30 <span word="DIDNT">DIDNT</span> <span word="SELECT">SELECT</span> <span word="ANY">ANY</span> <span word="SUBJECT">SUBJECT</span></p><p> 这种新<span word="GRE">GRE</span>数学考试题有两种解题方法：</p><p> 1)、概念法</p><p> <span word="P">P</span>=<span word="P">P</span>+<span word="P">P</span>-<span word="P">P</span></p><p> 以本题为例，至少学一科的=只学甲科+只学乙科-两科都学</p><p> 全集=<span word="A">A</span>+<span word="B">B</span>-<span word="A">A</span>交<span word="B">B</span>+非<span word="A">A</span>非<span word="B">B</span></p><p> <span word="normal">normal</span> <span word="distribution">distribution</span>下<span word="One">One</span> <span word="standard">standard</span> <span word="deviation">deviation</span> <span word="away">away</span> <span word="from">from</span> <span word="the">the</span> <span word="mean">mean</span>的<span word="possibility">possibility</span>为68%，<span word="Two">Two</span> <span word="standard">standard</span> <span word="deviation">deviation</span> <span word="away">away</span> <span word="from">from</span> <span word="the">the</span> <span word="mean">mean</span>的<span word="possibility">possibility</span>为95%，<span word="standard">standard</span> <span word="deviation">deviation</span> = 10。一种<span word="cougar">cougar</span>的体长呈正态分布，均值60英寸，问体长在70到80英寸之间的概率?</p><p> 落在平均值标准方差内的概率</p><p> <span word="possibility">possibility</span> == +=</p><p> 60-1060-102只落在一边的概率就要除以二，基本上这种题画一条数轴，做几个点会更一目了然一些。</p><p> /2 = 13.5</p><p> 2)、画图法</p><p> 画两个相交的圆<span word="A">A</span>、<span word="B">B</span>。圆<span word="A">A</span>下写学甲科的总数，圆<span word="B">B</span>下写学乙科的总数;两圆相交的部分写两科都学的数量，不相交的部分写各自只学一门的数量。再在外面画一个大方框，是学生总数，圆外方框内是什么都不学的。这样就一目了然了。</p>
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