请教3道PREP 的数学题

delia716

1. For all positive integers m, (m) ＝3m when m is odd and (m) = 1/2 m when m is even, which of the gollowing is equivalent to (9) x (6) ?

A)  (81)       (B)  (54)       (C)  (36)      (D)   (27)       （E）（18）

Answer is (D)

2. Malik's recipe for 4 servings of a certain dish requires 1 1/2 cups of pasta, accourding to this recipe, what is the number of cups of pasta that Malik will use the next time he prepare this dish?

(1) The next time he prepares this dis, Malik will make half as many servings as he did the las time he prepared the dish.

(2) Malik used 6 cups of pasta the last time he prepared this dish.

Answer is C.

3. What is the remainder when the positive integer x is divided by 3?

1) when x is divided 6 , the remainder is 2

2) when x is divided by 15, the remainder is 2.

Answer is D

这三道题我都没弄懂到底怎么回事， 哪为NN帮帮忙？ 谢谢谢谢 

delia716

自己顶一下

kevin_chee20

1. For all positive integers m, (m) ＝3m when m is odd and (m) = 1/2 m when m is even, which of the gollowing is equivalent to (9) x (6) ?

A)  (81)       (B)  (54)       (C)  (36)      (D)   (27)       （E）（18）

Answer is (D)

我认为可能条件给错了。如果按以上条件，Answer must be (A)

2. Malik's recipe for 4 servings of a certain dish requires 1 1/2 cups of pasta, accourding to this recipe, what is the number of cups of pasta that Malik will use the next time he prepare this dish?

(1) The next time he prepares this dis, Malik will make half as many servings as he did the las time he prepared the dish.

(2) Malik used 6 cups of pasta the last time he prepared this dish.

Answer is C.

答案应该是 C。 

这是一个对英语的理解问题。题目要问的是 the next time.  但是，题干只给出了菜谱（recipe）上的要求，再没有给出其他信息。

而条件（1）也只是给出了 next time 的使用量=last time Malik做的serving 需要量的half. 而 last time, Malik 做了多少serving 是没有给出数据的，therefore, （1） is not sufficent.

条件 （2）给出了the last time 的使用量，即，6 cups.  这个使用量除以菜谱上的使用量就得出last time 做了多少 servings. 但是，单独条件（2） 还是不能得出答案的

（a)和（b) together,  那么 next time 做了last time 的一半，那么，the number of cups of pasta that Malik will use 就可以得知。

3. What is the remainder when the positive integer x is divided by 3?

1) when x is divided 6 , the remainder is 2

2) when x is divided by 15, the remainder is 2.

Answer is D

带几个数字进去就可以得知，单独从条件（1）可以知道答案，单独从条件（2） 也可以知道答案， 所以 Anser is D

specters

第一题选D

(27)=81

kevin_chee20

请教一下 楼上NN，如何得出 （D）， 感谢！！！

噢！！！ 我明白了。(9)x(6)=m

[此贴子已经被作者于2006-10-16 11:06:03编辑过]

delia716

They are both understandable now.  Thank you very much!!

specters

以下是引用kevin_chee20在2006-10-16 11:04:00的发言：

请教一下 楼上NN，如何得出 （D）， 感谢！！！

噢！！！ 我明白了。(9)x(6)=m

[此贴子已经被作者于2006-10-16 11:07:26编辑过]