請教兩題pre中的題目

dirty64911

各位NN 請教一下兩題 pp的題目 --> 可能是我頭昏了吧 真是搞不懂  謝謝!

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 that 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.
Ans : D

A certain one-day seminar consisted of a morning session and an afternoon session. If each of the 128 people attending the seminar attended at least one of the two sessions, how many of the people attended the morning session only?

(1) 3/4 of people attended both sessions
(2) 7/8 of the people attended the afternoon session.
Ans : B

YY_lalala

up 先

lihong54

第一题是说， a square slab 的 cost和它的厚度成比例， 和长度也成比例。问，长3米，厚0.1米的square的cost？
条件1：长2m，厚0.2m的比长2米，厚0.1m的多花160。
设厚度和cost的比为x,那么0.2x=0.1x+160,可得出x=1600,得出cost是160。
条件2同理可得。

第二题画韦氏图，很容易出来.

kira_ke

顶