数学问题

cook

507. D .4
509. "if the sign is 3 centimeters long" - what does this mean?
     1.a+2r=3, a=2r--> r=3/4, a=3/2  then Volum=(3/2)^3+4*3/2*Pai*(3/4)^2/2  
                                               =3.375+1.6875Pai
     2. ...
Anyway, the question I can't understand. In addition," 3 centimeter",whcih I guess should be 3 meter.

510: C
541: E

Can u check our answer/ thanks!

劲松

以下数学问题出自新东方补充材料
我解出不同答案，但实在想不明白。费费的答案稍后公布，大家帮忙解解看

507
Three stacks containing equal numbers of chips are to be made from 9 red chips, 7 blue chips, and 5 green chips. If all of thes chips are used and each stack contains at least 1 chip of each color, what is the maximum number of red chips in any one stack?
A.7 B.6 C.5 D.4 E.3

509
The figure（就是一个正方形，每边外面加一个半圆的图形，看上去像个四瓣的花） shows the shape of a sign to be placed in front of a flower store. The sign has a semicirle on each side of the square, if the sign is 3 centimeters thick and if each side of the square is 50 centimeters long, what is the volume, in cubic centimenters. of the sign?
A.1250pi+2500 B.3750pi C.3750pi+7500 D.5000pi+7500 E.11250pi

510
What is the 1st term in sequence S?
(1)The 3rd term in S is 2
(2)The 2nd term in S is twice the 1st, and the 3rd term is three times the 2nd

541
A computer is programmed to generate a list of multiples of prime numbers 2, 3, and 5, as shown below:
-------------------------------------
Program 1-List multiples of 2
Program 2-List multiples of 3
Program 3-List multiples of 5
-------------------------------------
How many integers less than 100 will appear on all of the lists of programs produced above?
A.None B.1 C.3 D.5 E.An infinite number of integers

[此贴子已经被作者于2002-9-15 12:48:49编辑过]

劲松

对不起，昨天的509问题打掉了一段话，今天补上了

答案是CCEE

cook

507. sorry should be 5. According to context, 7 for each since equal number and total number of 21, First, 1 each color for each group.then go blue color, green , ans the last to distribute red.
  R   R      R   9-3=6
  B   B      B   7-3=4
  G   G      G   5-3=2
  4B 2G+2R  (6-2)R
Total
  7   7      7
So, the number of maximum red = ( 6-2)+1=5
509. Method: 50^2*3 + Pai*1/2*(50/2)^2*3*4 = 3750pi+7500 --> C
510. Are u sure?  My way goes like this:
(2) x, 2x, 3*2x  if 3*2x=2 --> x=1/3
Can u check it again? thanks!

劲松

我觉得自己好猪头啊，那么简单的题都做不对，完全是粗心，唉
谢谢cook兄的解释
510答案的确是E，我解出来也是C
541能解答一下吗？我脑袋堵上了，想不出来啊
郁闷ing............

brigittew

510，答案是C吧，1/3，怎么是E呢
541，我觉得问题主要是less than 100，没有给出明确的范围，我就错误的理解成0-100间能被2*3*5整除的数了，大家继续讨论

劲松

哎呀，是啊，没有说是正整数嘛，唉，我真是笨啊，郁闷.............

510我解出来也是1/3，但答案上就是E：（