10、(2007重庆)我市某镇组织20辆汽车装运完A、B、C三种脐橙共100吨到外地销售。按计划,20辆汽车都要装运,每辆汽车只能装运同一种脐橙,且必须装满。根据下表提供的信息,解答以下问题:

脐  橙  品  种
A
B
C
每辆汽车运载量(吨)
6
5
4
每吨脐橙获得(百元)
12
16
10

(1)设装运A种脐橙的车辆数为,装运B种脐橙的车辆数为,求之间的函数关系式;

(2)如果装运每种脐橙的车辆数都不少于4辆,那么车辆的安排方案有几种?并写出每种安排方案;

(3)若要使此次销售获利最大,应采用哪种安排方案?并求出最大利润的值。

解:(1)根据题意,装运A种脐橙的车辆数为,装运B种脐橙的车辆数为,那么装运C种脐橙的车辆数为,则有:

  整理得:

(2)由(1)知,装运A、B、C三种脐橙的车辆数分别为,由题意得:,解得:4≤≤8,因为为整数,所以的值为4、5、6、7、8,所以安排方案共有5种。

方案一:装运A种脐橙4车,B种脐橙12车,C种脐橙4车;

方案二:装运A种脐橙5车,B种脐橙10车,C种脐橙5车;

方案三:装运A种脐橙6车,B种脐橙8车,C种脐橙6车;

方案四:装运A种脐橙7车,B种脐橙6车,C种脐橙7车;

方案五:装运A种脐橙8车,B种脐橙4车,C种脐橙8车;

      (3)设利润为W(百元)则:

 ∴W的值随的增大而减小

要使利润W最大,则,故选方案一

=1408(百元)=14.08(万元)

   答:当装运A种脐橙4车,B种脐橙12车,C种脐橙4车时,获利最大,最大利润为14.08万元。

0.25小时另外4人步行了1.25km,此时他们与考场的距离为(km)

   ······························································································································ 7分

   设汽车返回后先步行的4人相遇,

   ,解得

   汽车由相遇点再去考场所需时间也是.······················································· 9分

   所以用这一方案送这8人到考场共需

   所以这8个个能在截止进考场的时刻前赶到.······················································· 10分

   方案2:8人同时出发,4人步行,先将4人用车送到离出发点处,然后这4个人步行前往考场,车回去接应后面的4人,使他们跟前面4人同时到达考场.···························································· 6分

   由处步行前考场需

   汽车从出发点到处需先步行的4人走了

   设汽车返回(h)后与先步行的4人相遇,则有,解得

······························································································································ 8分

   所以相遇点与考场的距离为

   由相遇点坐车到考场需

   所以先步行的4人到考场的总时间为

   先坐车的4人到考场的总时间为

   他们同时到达,则有,解得

   将代入上式,可得他们赶到考场所需时间为(分钟).

  

他们能在截止进考场的时刻前到达考场

6、(2007江西)某学校举行演讲比赛,选出了10名同学担任评委,并事先拟定从如下4个方案中选择合理的方案来确定每个演讲者的最后得分(满分为10分):

方案1  所有评委所给分的平均数.

方案2  在所有评委所给分中,去掉一个最高分和一个最低分,然后再计算其余给分的平均数.

方案3  所有评委所给分的中位数.

方案4  所有评委所给分的众数.

为了探究上述方案的合理性,先对某个同学的演讲成绩进行了统计实验.下面是这个同学的得分统计图:

(1)分别按上述4个方案计算这个同学演讲的最后得分;

(2)根据(1)中的结果,请用统计的知识说明哪些方案不适合作为这个同学演讲的最后得分.

解:(1)方案1最后得分:;··············· 1分

方案2最后得分:;····················································· 2分

方案3最后得分:;··································································································· 3分

方案4最后得分:.························································································· 4分

(2)因为方案1中的平均数受极端数值的影响,不能反映这组数据的“平均水平”,

所以方案1不适合作为最后得分的方案.······································································ 6分

因为方案4中的众数有两个,众数失去了实际意义,所以方案4不适合作为最后得分的方案.

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