NNs,请教几道Prep里面的数学题目

1.The cost of a square slab is proportional to its thickness and also proportional to the square of its length. What is the cost of a square slab that is 3 meters long and 0.1 meter thick?

1)The cost of a square slab that is 2 meters long and 0.2 meter thick is $160 more than the cost of a square slab that is 2 meters long and 0.1 meter thick.

2) The cost of a square slab is 3 meters long and 0.1 meter thick is $200 more than the cost of a square slab that is 2 meters long and 0.1 meter thick

answer

不明白这边 proportional to 指的是成比例呢还是直接就表示正比了阿？

不然怎么每个条件都可以直接求出比例系数来呢？？

2.Did one of  the 3 members of a certain team sell at least 2 raffle tickets yesterday?

1) The 3 members sold a total of 6 raffle tickets yesterday

2) No 2 of the members sold the same number of raffle tickets yesterday

answer

这题也是不太明白题目的意思啊~~~

Did one of  the 3 members of a certain team sell at least 2 raffle tickets yesterday?

这里说的是3个人中只要有一个是比2大的就可以了还是说3个人中至少都要大于二的呢？？

还有怎么两个都能成立的阿？？

3.Each employee on a certain task force is either a manager or a director. What percent of the employees on the task force are direcetors?

1) The average (arithmetric mean) salary of the managers on the task force is $5,000 less than the average salary of all employees on the task force.

2) The average (arithmetric mean) salsry of the directors on the task force is $15,000 greater than the average salary of all employees on the task force

answer:C

这题干脆完全不晓得怎么算了

NN们啊，开导我吧~~~！！！

怎么没有人理我啊，自己顶~~~~

看了半天:给点拙见

1 题目问的是成本与厚度和长度都成正比例    可以列等式  C=L^2 * T*K   C表示成本,L表示长度,T 表厚度, K表系数

              ( 1)  C1=2^2 *0.2 *K  C2=2^2 *0.1 *K   C1-C2= ^2 *0.2 *K-2^2 *0.1 *K=160,可求出系数K 那题    目的3M长,0.1厚, 按公式C=L^2 * T*K可求出C

               (2 )相同道理

                   所以选D

2题:题目问3人中至少有一人卖了2张票吗?

  (1)3个人总共卖了6张票,      你怎么分,都会有一人卖了2张票

   2)没有2个人卖同样数量的票,你假设最少一人卖1张,既然都不同,肯定其他的卖的比1张多

所以选D

3题:  我只知道式子怎么列,但不知道用简便方法计算

     题目说某项任务中,不是经理M就是董事D,问D占总人数的比例?

    1)M 的平均工资低于这帮人平均的5000

    2)D的平均工资高于这帮人平均的15000

     设平均工资V  ,M 人数是N1 ,工资是V1,   D 人数是N2,工资是V2

     V1=V-5000       (1)

       V2=V+15000    (2)

     V=(N1V1+N2V2)/(N1+N2)     (3)

     三个方程,四个未知数可以求出人任2个变量之间的关系,    所以 N1/N2就容易算出

茅塞顿开了~~

谢谢哈哈