高手帮忙解释下这3道数学。。小弟郁闷中。。

jerrylearner

A certain city with a population is ti be divide into 11 voting districts and no district is to have a population that is more than q0 percent grater than the population of any other district, what is the minimum possible population that the least populated district could have?

10700     10800    10900        11000            11100

for a finite sequence of nonzero numbers, the number of variations in sign is defined as the number of pairs if consecutive terms of the sequence for which the product of the two consecutive is negative. Which is the number of variation in sign for the sequence 1, -3,2,5,-4,-6?

One

 two

three

four

five .  

if n and y are positive integers and 450y =n^3, which of the following must be an integer?

1)y/3*2^2*5 

2)y/3^2*2*5

3)y/ 3*2*5^2

Sophia0703

以下是引用jerrylearner在2008-12-27 8:15:00的发言：

1.A certain city with a population is ti be divide into 11 voting districts and no district is to have a population that is more than q0 percent？？？ grater than the population of any other district, what is the minimum possible population that the least populated district could have?

10700     10800    10900        11000            11100

2.for a finite sequence of nonzero numbers, the number of variations in sign is defined as the number of pairs if consecutive terms of the sequence for which the product of the two consecutive is negative. Which is the number of variation in sign for the sequence 1, -3,2,5,-4,-6?

One

 two

three

four

five .  

是3吗？

是的话就是（1，-3）（-3，2）（5，-4）

3.if n and y are positive integers and 450y =n^3, which of the following must be an integer?

1)y/3*2^2*5 

2)y/3^2*2*5

3)y/ 3*2*5^2

450Y=N^3=3^2*2*5^2   带进去可以化简吧

jerrylearner

多谢ls

第一题 是

A certain city with a population is ti be divide into 11 voting districts and no district is to have a population that is more than 10 percent grater than the population of any other district, what is the minimum possible population that the least populated district could have?

10700     10800    10900        11000            11100

Sophia0703

以下是引用jerrylearner在2008-12-29 2:42:00的发言：

多谢ls

第一题 是

A certain city with a population is ti be divide into 11 voting districts and no district is to have a population that is more than 10 percent grater than the population of any other district, what is the minimum possible population that the least populated district could have?

10700     10800    10900        11000            11100

额...想问下有没有漏条件？感觉是不是要告诉一共多少人啊？

就这个还真不懂算耶~

还是牛牛们来吧~

jerrylearner

牛年啦  牛牛们快来帮忙 。。 。 至今这道题  还是一头雾水

rosyrosy00

楼主你那个第一题少条件的，没告诉总人数怎么可能知道least的人数，最least么就是1.。。。

这个题目好像是prep里有的

lucyliu

The 1st question missed one condition: the sum of the population is 132,000.

because we need "the minimum possible population that the least populated district", so

set it as x, and the rest as 1.1x, therefore, we have:

x+10*1.1x=132000 => x=11,000

It is a Q in Prep~