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三大類GRE數(shù)學題型舉例分析

發(fā)布時間:2017-04-13 編輯:梁雅

  下面是小編針對GRE數(shù)學考試中的無選項計算題、多項選擇題和判斷題這三類題型進行解析,希望能夠幫助考生更好的準備GRE數(shù)學考試。

  GRE數(shù)學題目之無選項計算題

  例:The average(arithmetic mean)of the 11numbers in a list is 14. If the average of 9 of thenumbers in the list is 9,what is the average of theother 2 numbers?(11個數(shù)的算術平均數(shù)是14。若其中9個數(shù)的算術平均數(shù)為9,則剩下的2個數(shù)的平均數(shù)是多少?

  這個GRE數(shù)學考試樣題考察的是考生對算術平均值這一概念的認識。如果N個數(shù)的算術平均是X,則這N個數(shù)之和為NX。只要掌握了這一點對于那些考察算術平均值的題目就應該迎刃而解了。從這里我們也可以看出在改革后的GRE數(shù)學中,對于一些統(tǒng)計學數(shù)值(比如算術平均、極差、標準方差、中數(shù)等)的理解要求提高了。

  GRE數(shù)學題目之多項選擇題

  例:In triangle ABC,the measure of angle A is 25 and the measure of angle B isGREater than 90. Which of the following could be the measure of angle C?

  Indicate all possible values.

  A. 12 B. 15C. 45  D. 50 E.70

  本題考察的是三角形的基本性質:內角和等于180度。由題意可知角A角B之和大于115度,由此可以得出A、B、C、D為正確答案。

  由于GRE數(shù)學考試本身考察的數(shù)學知識并沒有變難,所以這種題型僅僅是增加了考生思維的復雜性,并要求考生更加細心。

  GRE數(shù)學題目之判斷題

  例:The symbol ? represents one of the four operations of addition, subtraction,multiplication, and division, and 3 ? 1 = 3.

  For each of the following equations, indicate whether the equation must be true, must befalse, or could be either true or false.

  Equation

  Must Be True

  Must Be False

  Could Be True or False

  6 ? 2 = 3

  6 ? 2 = 4

  6 ? 2 = 12

  Click on your choices.

  Click on the answer box, then type in a number. Backspace to erase.

  GRE中出現(xiàn)的非常規(guī)數(shù)學符號可以看成ETS自己定義的一種運算。本題中,符號“?”代表的是加減乘除四種四則運算中的某一種,而且3?1=3,由這些已知條件可以推出?可以是,也可以不是。接下來就考察考生對于must be true、could be true這類邏輯判斷語言的理解了。Must be true意為必然正確,在任何時候都不可違背;Could be true意為可以正確,即存在正確的可能。

  因此第一個等式6?2=3在?代表除時錯誤,但在?代表加、減、乘時正確,因此第一式應為could be trueor false有可能對也可能錯;

  第二個等式6?2=4不論?代表什么都不正確,因此第二式應為must be false一定錯誤;

  第三個等式6?2=12在?代表乘時正確,但在?代表加、減、除時錯誤,因此第三式同第一式一樣,也是有可能對也有可能錯。

  延伸閱讀:

  本文為大家準備了GRE數(shù)學考試重要考點知識,便于考生GRE考試備考。

  Set

  A set is a collection of objects or things. Eachobject in a set a member or element of that set.Sizeof a set is the number of members in the set.

  Example:

  The set of even numbers between 2 and 10 is ofsize 5:{2,4,6,8,10}.

  The set of primes between 2 and 10 is of size 4:{2,3,5,7}.

  Remember:

  Each member of set A belongs to A or is in the set A.

  A set can not have repeating member:{1,3,1,2}is not a set.

  Rearranging the order of the members does not change the set:{1,2,3}is same as{3,2,1}.

  Combinations

  Number of ways we can select n objects from a group of m distinct objects is m!/(n!*(m-n)!).

  Example:

  Number of possible ways to pick 4 oscar nominations from a list of 50 movies is 50!/(4!*(50-4)!)=50!/(4!*46!)=50*49*48*47/24=230300.

  Remember:

  This does not apply if there are identical objects.

  Permutation of Objects

  The number of ways n distinct objects can be ordered is n.

  Example:

  Number of ways 6 people can from a queue is 6.

  Number of ways 5 different cars can be parked in 5 parking spaces is 5.

  Remember:

  This does not apply if there are identical objects or ordering does not matter.

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