GWD15 错得想跳楼~! 麻烦大侠救命

onopan

快要考试了,GWD15 居然数学错了7个,差点气得昏过去;更气的是,发现自己真的做不来,比如:

Q2:

A certain characteristic in a large population has a distribution that is symmetric about the mean m.  If 68 percent of the distribution lies within one standard deviation d of the mean, what percent of the distribution is less than m +
                    d ?

 

A.    16%

B.     32%

C.     48%

D.    84%

E.     92%

Answer:

答案是D

这题怎么做的啊

还有下题, 看也看不懂,,,,,

Q29:

The toll for crossing a certain bridge is $0.75 each crossing.  Drivers who frequently use the bridge may instead purchase a sticker each month for $13.00 and then pay only $0.30 each crossing during that month.  If a particular driver will cross the bridge twice on each of x days next month and will not cross the bridge on any other day, what is the least value of x for which this driver can save money by using the sticker?

 

A.    14

B.     15

C.     16

D.    28

E.     29

honglei

第一题  68 在mean+d 以内  你画个图 中间是mean  两边各加d 然后那部分便是68 一半34

然后m+d 就是 50（mean）+34（一半）=84

第二题 设天数为x

13+2*0.3x<=0.75*2*x

x>=14.4

是b吧？

fzxc613

数学没必要作，考试前看看ｊｊ就行了。我高考数学才考了９０分。

fzxc613

别在这上面浪费时间浪费心情，没用

nopanicfan

数学7个应该是有50分吧..GWD数学..我感觉没有太大做的必要....但是只是个人认为.

onopan

懂了~谢谢honglei~ 谢谢各位~