ＰＰ３ 数学几个不知道的题目

liming21

1,For every positive even integer n, the function h(n) is defined to be the product of all the even integers from 2 to n, inclusive, If p is the smallest prime factor of h(100) +1, then p is

 

A between 2 and 10

B between 10 and 20

C between 20 and 30

D greater than 40

 

Answer

 

2 If each term in the sum a1 +a2+…..An is either 7 or 77 and the sum equals 350, which of the following could be equal to n?

A 38

B 39

C 40

 

Answer 40

 

 

4, A certain city with a population of 132,000 is to be divided into 11 voting districts, and no districts is to have a population that is more than 10 percent greater than the population of any other district. What is the minimum possible population that the least populated district could have?

A 10700

B 10800

C 10900

D 11000

 

 

Answer d

 

110.  11364-!-item-!-187;#058&007646

The residents of Town X participated in a survey to determine the number of hours per week each resident spent watching television.  The distribution of the results of the survey had a mean of 21 hours and a standard deviation of 6 hours.  The number of hours that Pat, a resident of Town X, watched television last week was between 1 and 2 standard deviations below the mean.  Which of the following could be the number of hours that Pat watched television last week?　（这个题目真是不知道怎么写了，什么叫比平均值小１－２个标准差？）

 

(A) 30

(B) 20

(C) 18

(D) 12

(E) 6

liming21

ding

gyyygyyy

第1题：h(100) +1=2*4*6*……*100+1=2(1*2*3*……*50)+1

因为相邻两个数的最大公约数是1，且2(1*2*3*……*50)的约数为1--50，

所以2(1*2*3*……*50)+1的约数肯定大于50，所以选D

第2题：N个尾数为7的数字相加最后等于尾数为0的数，那么这个N肯定10的倍数，所以选C

第4题：设a为最小的地区人口数，那么最大的地区人口数就是1.1a，要想a最小，则其他9个地区的人口数都是1.1a，所以a+1.1a*10=12a=132000，a=11000

第110题：比平均值小１－２个标准差，就是比21小1*6--2*6，所以就是15--9的范围，选D

[此贴子已经被作者于2008-12-8 12:07:21编辑过]