[求助]求助两道prep数学，prep-1-98，prep-1-121

rainyrenren

prep-1-98:

98.If x is a negative integer, which of the following expressions has the LEAST value?

(A) x2 - 0.50

(B) x2 - 0.51

(C) x3 - 0.502

(D) x3 - 0.511

(E) x4 - 0.512

答案是D

prep-1-121:

121.A vending machine is designed to dispense 8 ounces of coffee into a cup.  After a test that recorded the number of ounces of coffee in each of 1,000 cups dispensed by the vending machine, the 12 listed amounts, in ounces, were selected from the data.    If the 1,000 recorded amounts have a mean of 8.1 ounces and a standard deviation of 0.3 ounce, how many of the 12 listed amounts are within 1.5 standard deviations of the mean?

(A) Four

(B) Six

(C) Nine

(D) Ten

(E) Eleven

答案是E

谢谢啦！！

[此贴子已经被作者于2008-7-19 2:10:33编辑过]

rainyrenren

发表这帖子，改了好几遍，可是这个帖子第二题的选项重复了，多余的那串死活删不了，大家凑合看吧，拜托了，帮忙解一下~~

ellen87

第一题X是负数，那么X偶次方是正数，X的奇次方是负数，所以答案可以排除A B  Ｅ，　X三次方-0.502 大于 X三次方-0.511  （负数比较大小，绝对值越大，实际值越小）所以选Ｄ

[此贴子已经被作者于2008-7-19 2:16:41编辑过]

rainyrenren

谢谢， x2 - 0.50 这种写法是x的2次方的意思呀.....谢谢！

rainyrenren

第二题谁能帮帮忙呀....拜托了！

rainyrenren

谁会第二题呀？急呀..

js9

楼主哪里找到的PREP的数学破解版？
能告诉我吗？
我也想要
··、、、


谢谢

rainyrenren

你加我qq吧，我给你发过去...这个论坛上传我不会使...54281643

jh1904

Please provide the 12 listed amounts. The question is incomplete without the 12 listed amounts and can not be answered.

rainyrenren

哦，那就是这题本身的问题了....知道了，谢谢！