请教Pre中的数学题

tracyforever

小女子。。。请教以下4题，谢谢！

1-- A certain list consists of several different integers, is the product of all the integers in th elist positive?
(1) The product of the greatest and smallest of the integers in the list is positive
(2) There is an even number of integers in the list
Both (1) and (2) together are sufficient, but neither statement alone is sufficient.

2-- For any positive integer, the length of n is defined as the number of prime factors whose product is n. For example, the length of 75 is 3, since 75=3*5*5. How many two digit positive integers have length 6?
Two

3-- If m is a positive odd integers, what is the average (arithmetic mean) of a certain set of m integers?
(1) The integers in the set are consecutive multiples of 3
(2) The median of the set of integers is 33
Both (1) (2) together are sufficient

4-- A certain business produced X rakes each month from Nov. through Feb. and shipped x/2 rakes at the beginning of each month from Mar. through Oct.. The business paid no storage for the rakes from Nov. through Feb., but it paid storage costs og $0.10 per rake each month from Mar. through Oct. for the rakes that had not been shipped. In terms of x, what was the total storage cost i dollars that the business paid for the rakes for 12 months from Nov. through Oct.
1.4x

tracyforever

谢谢。。。

shirleyyao

1、条件一， list中最大数和最小数乘积为正，则这个list可能全为正或负，不能确定乘积正负
    条件二， list中数的个数是偶，那即使所有的数都是负数，乘积也一定是正
    所以选C

2、 2*2*2*2*2*2 或是 2*2*2*2*2*3
3、 这个数列是以33为中数的等差数列，只要知道数列中数的个数为奇，则平均数=中数
4、 11月-2月 生产 4x
      5月-10月 装船销售玩全部的货
     则库存费=(3.5x+3x+2.5x+2x+1.5x+1x+0.5x)*0.1=1.4x