攒RP贴！！应要求改为大家攒RP贴 讨论数学问题 帮忙解答或提出疑问 LZ 不是NN 但做最大的努力帮大家解答数学问题。

yyx

楼主好人，我想问一个当月狗。
DS，是P,Q,R,S四个数，貌似是正实数，问 is P%of Q less than R% of S?
条件一是0<p<r^2<q<s^2
条件二是0<p^2<r<q^2<s
二十好考，多谢楼主啦！

-- by 会员 爱上薰衣草的紫 (2010/10/18 18:52:34)

请问答案是B吗？

-- by 会员 yyx (2010/10/18 19:05:58)

狗狗没有答案~~~

-- by 会员 爱上薰衣草的紫 (2010/10/19 18:27:02)

答案是E
1：如果prqs：1283 就大于  prqs：1243就小于  因此不sufficient
2: 如果pqrs:0.1 0.2 3 10 就 小于 如果pqrs:0.1 0.02 3  10 就大于 因此 不sufficient

-- by 会员 yyx (2010/10/19 18:47:02)

改正 1243 改成 1253好了  反正答案还是E  关键是找反列  你明天考啦？  加油加油

-- by 会员 yyx (2010/10/19 18:49:32)

这题我感觉，1.2一起是充分的。
1.2可以想乘的，因为都大于0，符号不变，这样P^3<R^3   得到P<R,同理Q<S
这两个式子再相乘。PQ<RS

你看看有没有问题。

-- by 会员 daniel123 (2010/10/21 18:40:15)

嗯嗯 应该是这样的 答案是C

discoguo

Dear LZ,

If n and y are positive integers and 450y = n³, which of the following must be an integer?



I.   y / (3*2^2*5)  

II.  y / (3^2*2*5)
II.  y / (3*2*5^2)



(A) None

(B) I only

(C) II only

(D) III only

(E) I, II, and III


答案是B……
我得出y=n^3/450 =n^3/(3^2*2*5^2)
I 推出 n^3/(3^3*2^3*5^3) 但是这就一定可以整除吗？

请赐教~~

discoguo

还有一道：

62.7564-!-item-!-187;#058&005577

Alice
's take-home pay last year was the same each month, and she saved the same fraction of her take-home pay each month.The total amount of money that she had saved at the end of the year was 3 times the amount of that portion of her monthly take-home pay that she did not save.If all the money that she saved last year was from her take-home pay, what fraction of her take-home pay did she save each month?


(A) 1/2

(B) 1/3

(C) 1/4

(D) 1/5

(E) 1/6

我列出： P * x% * 12=3* (1-x%) * 12 怎么算x都=3/4

请指点~~
有劳了，谢谢啦！~~

yiyisue

lz还有几个题请教啊！
首先是几个关于余数的问题，这类题目总是不会，希望lz指点一下拉~~
What is the remainder when the two digit, positive integer x is divided by 3?
(1)      The sum of the digits of x is 5.
(2)      The remainder when x is divided by 9 is 5.
答案D
If n is a positive integer and r is the remainder when (n-1)(n+1) is divided by 24, what is the value of r?
(1)      2 is not a factor of n.
(2)      3 is not a factor of n.
答案C
还有一道数列的
If r is a constant  and an = r?n for all positive integers n, for how many values of n is an < 100?
(1)      a50 = 500
(2)      a100 + a105 = 2,050
答案D
How many seconds will it take for a car that is traveling at a constant rate of 45 miles per hour to travel a distance of 22 yards?    (1 mile = 1,160 yards)这道题我怎么算都是1.5多，答案是10。。我是3600*22/{45*1160}这样算的。。不知道哪里错了呢？
辛苦楼主了！！

tgoz

还有一道：

62.7564-!-item-!-187;#058&005577

Alice
's take-home pay last year was the same each month, and she saved the same fraction of her take-home pay each month.The total amount of money that she had saved at the end of the year was 3 times the amount of that portion of her monthly take-home pay that she did not save.If all the money that she saved last year was from her take-home pay, what fraction of her take-home pay did she save each month?


(A) 1/2

(B) 1/3

(C) 1/4

(D) 1/5

(E) 1/6

我列出： P * x% * 12=3* (1-x%) * 12 怎么算x都=3/4

请指点~~
有劳了，谢谢啦！~~

-- by 会员 discoguo (2010/10/21 20:46:18)

MM，这个题目有陷阱哦，文中说的是一年节省的总量3倍于其一个月的没有节省的部分
所以是 P * x% * 12=3*P (1-x%)   右边不需要乘以12了呢
X=1/5

yyx

等我一下马上回来帮大家解答！

yyx

Dear LZ,

If n and y are positive integers and 450y = n³, which of the following must be an integer?



I.   y / (3*2^2*5)  

II.  y / (3^2*2*5)
II.  y / (3*2*5^2)



(A) None

(B) I only

(C) II only

(D) III only

(E) I, II, and III


答案是B……
我得出y=n^3/450 =n^3/(3^2*2*5^2)
I 推出 n^3/(3^3*2^3*5^3) 但是这就一定可以整除吗？

请赐教~~

-- by 会员 discoguo (2010/10/21 20:43:00)

请问这个原题在哪里的 题目本身是这个意思么？

chasechase12

感激啊!!




1.If it took Tom 0.5hour to cycle from his house to the library. was the distance that he cycled greater than 6 miles?

  (1) the average speed at which Tom great than 16 feet per second.
  (2) the average speed at which Tom less than 18 feet per second.

 ANS:E

2.If a certain sample of data has a mean of 20 and a standard deviation of 3. which of the following values is more than 2.5 standard deviation from the mean.

ANS: 12

3.How many hours did it take Tom to drive from her house to her parent's home?

  (1)Tom's average speed on this trip was 72km per hours.
  (2)If Tom's average speed on this trip had been 8km per hour greater, it would take her 1 hour less.    ANS:  C

4.Alice's take-home pay last year was the same each month, and she saved the same fraction of her take-home pay each month. The total amount of money that she had saved at the end of the years was 3 times the amount of that portion of her monthly take-home pay that she did not save. If all the money that she saved last year was from her take-home pay. what fraction of her take-home pay did she save each moth?

ANS: 1/5

yyx

lz还有几个题请教啊！
首先是几个关于余数的问题，这类题目总是不会，希望lz指点一下拉~~
What is the remainder when the two digit, positive integer x is divided by 3?
(1)      The sum of the digits of x is 5.
(2)      The remainder when x is divided by 9 is 5.
答案D
If n is a positive integer and r is the remainder when (n-1)(n+1) is divided by 24, what is the value of r?
(1)      2 is not a factor of n.
(2)      3 is not a factor of n.
答案C
还有一道数列的
If r is a constant  and an = r?n for all positive integers n, for how many values of n is an < 100?
(1)      a50 = 500
(2)      a100 + a105 = 2,050
答案D
How many seconds will it take for a car that is traveling at a constant rate of 45 miles per hour to travel a distance of 22 yards?    (1 mile = 1,160 yards)这道题我怎么算都是1.5多，答案是10。。我是3600*22/{45*1160}这样算的。。不知道哪里错了呢？
辛苦楼主了！！

-- by 会员 yiyisue (2010/10/22 22:31:59)

第一题： 1.因为2位数 两个数字加起来是5 那么可以列举出 23 32 14 41 50 恰好余数都是2。 2.这个数字可以表示为9k+5, 于是除以3时就是3*（3k+1）+2 余数就是2 于是选D
第二题：

如果 2 不是 n 的因数，那么 n 就是单数了。所以 n - 1 和 n + 1 一个是 2  的倍数，一个是 4  的 倍数，那么 (n - 1)(n + 1) 就一定是 8 的倍数了。

如果 3 不是 n 的因数，那么 n - 1 和 n + 1 其中一个一定是 3  的倍数，那么 (n - 1)(n + 1) 就一定是 3 的倍数了。

所以 (1) 和 (2) 同时使用，就能够证明  (n - 1)(n + 1) 一定是 24 的倍数了。所以 r = 0。第三题：
1.这个就是a50=r*50=500 得出r=10  
 2.a100+a105=2050 所以205r=2050 所以r=10 知道r的值就知道个数了


第四题： 1 mile = 1760 yard 所以22/1760/46*3600=0.978264=10这样吧

chasechase12

請教97樓 四題~~~