asking for answer for new pp3 math.

simonjo

1. of the 60 animals on certain farm, 2/3 are either cows or pigs. How many of animal are cows?

     (1) The farm has more than twice as many cows.

      (2) the farm has more than 12 pigs

(C)

2.if n and m are positive integer, what is remainder when 3^4n+2 is divided by 10.

   (1) n =2

    (2) m=1

(B)

(it is strange that there are no "m" metioned in the question)

3. on the number line, distance between X and Y is greater than distance between x and z, does z line between x and y on the number line?

   (1). xyz<0

    (2) xy<0

(E)

seasnow

第2题应该是3^(4n+2)+m吧，这道题在哪里见过。

simonjo

You are right. that seems ok to me. why does offical GMAT prep have such error?  

seasnow

I wonder why either.

Should we write a letter to question the test company(I still cannot remember its name)?

sunnybright

1. of the 60 animals on certain farm, 2/3 are either cows or pigs. How many of animal are cows?

     (1) The farm has more than twice as many cows.(这是啥意思啊？是不是漏了什么,maybe has pigs more than twice as many cows? 不过我也还是解不出来）

      (2) the farm has more than 12 pigs

simonjo

math nn!! come to help!!

yannis

let C be no of cows, P be no of pigs. P+C = 60 x 2/3 = 40

For (1), P>2C, as only >, then no of P is at least 21 or above and C is atmost 40-21=19, can't determine the exact no of cows.

For (2), P>12, no result can be reached.

considering (1)+(2),

(P,C) might be (21, 19), (22,18), (23, 17), (24, 16), (25,15), (26,14), (27,13).

only (27, 13) fits the criteria of P>2C

I am not sure whether it is the quickest way to get the answer, but hope it is helpful

titatita

以下是引用simonjo在2006-1-9 23:30:00的发言：

1. of the 60 animals on certain farm, 2/3 are either cows or pigs. How many of animal are cows?

     (1) The farm has more than twice as many cows.

      (2) the farm has more than 12 pigs

(C)

这题条件1不全吧.应该是the farm has pigs more than twice  as many as cows?p是c得两倍?

条件2是不是more than 12 c啊?

如果是这样得,就可以解了.

根据条件p+c=40

且 p>2c,c>12

用列举法很快就可作出答案.如果p=2c c=40/3=13.333那么从p=2c=27开始列举,c=13;p=28,c=12不符合c>12条件所以有唯一解c=13;p=28

2.if n and m are positive integer, what is remainder when 3^4n+2 is divided by 10.

   (1) n =2

    (2) m=1

(B)

(it is strange that there are no "m" metioned in the question)

题目肯定有误,3^4n+m?或其他得 newpp3里确实有bug

3. on the number line, distance between X and Y is greater than distance between x and z, does z line between x and y on the number line?

   (1). xyz<0

    (2) xy<0

(E)举反例可得

titatita

以下是引用yannis在2006-1-10 9:47:00的发言：

let C be no of cows, P be no of pigs. P+C = 60 x 2/3 = 40

For (1), P>2C, as only >, then no of P is at least 21 or above and C is atmost 40-21=19, can't determine the exact no of cows.

For (2), P>12, no result can be reached.

considering (1)+(2),

(P,C) might be (21, 19), (22,18), (23, 17), (24, 16), (25,15), (26,14), (27,13).

only (27, 13) fits the criteria of P>2C

I am not sure whether it is the quickest way to get the answer, but hope it is helpful

怀疑条件2为c>12

否则你这个由调件1

(P,C) might be (21, 19), (22,18), (23, 17), (24, 16), (25,15), (26,14), (27,13).(28,12)(29,11)......

如果调件2是p>12得话(27,13).(28,12)(29,11)......都可以啊