问:
王文静老师麻烦教一下这道题目,我选了b,排除了a,因为我觉得a里面不能用it,1990-2000的经济和农耕文化开始的1000年里面的经济不一样啊,it不是指 between 1990 and 2000 the global economy吗,我觉得要用that.就比如一道小汽车的题目(见下图):由于现代技术的发展,现在的小汽车要比以往任何时候的小汽车都省油。这个小汽车就是不同时代的比较啊。然后c我排除的原因是that which had been时态不对,d it has been这里面的it指的是前面的the growth of the global economy between 1990 and 2000, E名词和主谓比不对等。不知道这样看对吗?
GMAT数学(博智教材)第62页:If X is equal to the sum of the even integers from 40 to 60, inclusive, and y is the number of even integers from 40 to 60, inclusive, what is the value of x+y?
X=40+42+44......60=550
Y=(60-40)/2+1=11, 答案应该是561,为什么书后面的答案显示是560?
DS:5个数中 median 小于 average ;另外7个数也median 小于 average,然后这12个数没有重复的,12个数放在一个数集里面,问是不是median 小于average?
条件1:7个的average 小于 5个的average
条件2:7个的median 小于 5个的 median
题目:of the 200 students at college T majoring in one or more of the sciences, 130 are majoring in chemistry and 150 majoring in biology. If at least 30 of the students are not majoring in either chemistry or biology, then the number students majoring in both biology and chemistry could be any number from
a) 20 to 50
b) 40 to 70
c) 50 to 130
d) 110 to 130
e) 110 to 150
问题:这道题能理解到是用集合的知识点,但是无论怎么做都无法突破,得到最后结果。还请老师讲解。谢谢