請教幾題pp test2數學

[stilalala]

#17
What is the average height of the n people in a certain group ?

(1) The average height of the n/3 tallest people in the group is 6 feet 2 1/2 inches , and the average height of the rest of the people in the group is 5 feet 10 inches

(2) The sum of the height of the n people is 178 feet 9 inches

ans :a

我想要請問各位大大,(1)表達的意思,是指全部裡面最高的人,還是n人裡面最高的n/3個人的平均身高
看得我都昏了


#20
In the fraction x/y ,where x, y both are positive inetgers, ask y=?

(1)the least common denominator of x/y and 1/3 is 6
(2)x=1

ans: e

請問是因為y可以為2,也可能為6 所以無從判斷嗎

#27
If m and r are 2 numbers on the number linw, r=?
(1) The distance between r and 0 is 3 times the distance between m and o

(2)12 is halfway between m and r

ans :e

請問是因為0的位置不定,且不知道m,r的相對大小的關係嗎

#29
If the drama club and music club are combined, what percent of the combined membership will be male?

(1)of the 16 members of the drama club , 15 are male

(2) of the 20 members of the music club, 10 are male

ans:e

又被of,搞得頭昏了
請教為何不能(1)+(2)求出

感謝

[stwang]

#17
What is the average height of the n people in a certain group ?

(1) The average height of the n/3 tallest people in the group is 6 feet 2 1/2 inches , and the average height of the rest of the people in the group is 5 feet 10 inches

(2) The sum of the height of the n people is 178 feet 9 inches

ans :a

我想要請問各位大大,(1)表達的意思,是指全部裡面最高的人,還是n人裡面最高的n/3個人的平均身高
看得我都昏了

我覺得它的意思是N人裡面最高的N/3個人的平均身高
算法如下:
1 foot =12 inches
6feet 2 1/2inches= 74.5 inches
5feet 10inches= 70 inches
[n/3*74.5+2n/3*70]/n=71.5

#20
In the fraction x/y ,where x, y both are positive inetgers, ask y=?

(1)the least common denominator of x/y and 1/3 is 6
(2)x=1

ans: e

請問是因為y可以為2,也可能為6 所以無從判斷嗎

同意.. 我想是因為這樣所以(1)不充分

#27
If m and r are 2 numbers on the number linw, r=?
(1) The distance between r and 0 is 3 times the distance between m and o
(2)12 is halfway between m and r

ans :e
請問是因為0的位置不定,且不知道m,r的相對大小的關係嗎

(1)lr-0l=3lm-0l r和m不充分
(2)(r+m)/2=12 r+m=24 不充分
(1)+(2) r=3m 代入r+m=24 r=6 m=18
r=-3m 代入r+m=24 r=36 m=-12 所以不充分
正確答案為E

#29
If the drama club and music club are combined, what percent of the combined membership will be male?

(1)of the 16 members of the drama club , 15 are male

(2) of the 20 members of the music club, 10 are male

ans:e

又被of,搞得頭昏了
請教為何不能(1)+(2)求出

題目是在問兩個club合起來male佔百分之幾
我在想會不會是因為他們有沒有交集的關係壓
如果male有人參加drama club 和music club 那即使有1,2條件也求不出來
一點小意見 不知道對不對 給你參考唷...
感謝

[stilalala]

#17
What is the average height of the n people in a certain group ?

(1) The average height of the n/3 tallest people in the group is 6 feet 2 1/2 inches , and the average height of the rest of the people in the group is 5 feet 10 inches

(2) The sum of the height of the n people is 178 feet 9 inches

ans :a

我想要請問各位大大,(1)表達的意思,是指全部裡面最高的人,還是n人裡面最高的n/3個人的平均身高
看得我都昏了

我覺得它的意思是N人裡面最高的N/3個人的平均身高
算法如下:
1 foot =12 inches
6feet 2 1/2inches= 74.5 inches
5feet 10inches= 70 inches
[n/3*74.5+2n/3*70]/n=71.5

#20
In the fraction x/y ,where x, y both are positive inetgers, ask y=?

(1)the least common denominator of x/y and 1/3 is 6
(2)x=1

ans: e

請問是因為y可以為2,也可能為6 所以無從判斷嗎

同意.. 我想是因為這樣所以(1)不充分

#27
If m and r are 2 numbers on the number linw, r=?
(1) The distance between r and 0 is 3 times the distance between m and o
(2)12 is halfway between m and r

ans :e
請問是因為0的位置不定,且不知道m,r的相對大小的關係嗎

(1)lr-0l=3lm-0l r和m不充分
(2)(r+m)/2=12 r+m=24 不充分
(1)+(2) r=3m 代入r+m=24 r=6 m=18
r=-3m 代入r+m=24 r=36 m=-12 所以不充分
正確答案為E

#29
If the drama club and music club are combined, what percent of the combined membership will be male?

(1)of the 16 members of the drama club , 15 are male

(2) of the 20 members of the music club, 10 are male

ans:e

又被of,搞得頭昏了
請教為何不能(1)+(2)求出

題目是在問兩個club合起來male佔百分之幾
我在想會不會是因為他們有沒有交集的關係壓
如果male有人參加drama club 和music club 那即使有1,2條件也求不出來
一點小意見 不知道對不對 給你參考唷...
感謝

謝謝你
我懂了

[chris8888]

least common denominator是最小公分母, 是意思說, 乘上它可以讓屬於這個最小公分母的分數變成整數, 因此
1/y and 1/3 擁有最小公分母6, 將6做因式分解, 有factors 1, 2, 3, 6, 因為x/y是分數, 所以排除1, 又因為1/3 and 1/3的最小公分母不會是6, 是3, 所以剩下1/2 and 1/6, 兩個答案, insufficient, 因此答案是E

[chris8888]

458. If m and r are 2 numbers on the number line, r=?

(1) The distance between r and 0 is 3 times the distance between m and 0 or o
(2)12 is halfway between m and r

是o or 0, 上面的大大有貼錯嗎? 應該是0吧, 看算式應該是.

[chris8888]

If the drama club and music club are combined, what percent of the combined membership will be male?

(1)of the 16 members of the drama club , 15 are male

(2) of the 20 members of the music club, 10 are male

from (1), 15/16 => male ; so insufficient
from (2), 10/20 => make ; so insufficient
from (1) + (2), 假設drama有x人, male => 15/16x
假設music 有y人, male => 10/20y
what percent of the combined membership will be male => (15/16x + 10/20y) / x + y 算不出, insufficient


ans:e

[emmaaqua]

If the drama club and music club are combined, what percent of the combined membership will be male?

(1)of the 16 members of the drama club , 15 are male

(2) of the 20 members of the music club, 10 are male

from (1), 15/16 => male ; so insufficient
from (2), 10/20 => make ; so insufficient
from (1) + (2), 假設drama有x人, male => 15/16x
假設music 有y人, male => 10/20y
what percent of the combined membership will be male => (15/16x + 10/20y) / x + y 算不出, insufficient


ans:e

我想請問一下chris8888~
條件1.2的意思不是說drama club一共16人跟music club一共20人嗎?

不太懂....謝謝~^^

[chris8888]

If the drama club and music club are combined, what percent of the combined membership will be male?

(1)of the 16 members of the drama club , 15 are male

(2) of the 20 members of the music club, 10 are male

from (1), 15/16 => male ; so insufficient
from (2), 10/20 => make ; so insufficient
from (1) + (2), 假設drama有x人, male => 15/16x
假設music 有y人, male => 10/20y
what percent of the combined membership will be male => (15/16x + 10/20y) / x + y 算不出, insufficient


ans:e

我想請問一下chris8888~
條件1.2的意思不是說drama club一共16人跟music club一共20人嗎?

不太懂....謝謝~^^

抱歉, 我第二次做到這一題, 又錯了. 經過我在網路上的研究, 有兩種觀點
1. 就語文上來說
(1) of the 16 members of the drama club , 15 are male of the 16 members of => among the 16 members of
解釋為, 在drama的16個成員裡面, 有15個是男生. 原先drama可能有35人. 他似乎只給比例.
或者
另有一說是 : 兩個俱樂部的人有重複的, 因此不能計算.

[小花]

問過AT老師 意思是:

總共有16個drama成員, 其中15個是男性

把句子重新組裝一下就很容易理解了
原句：
Of the 16 members of the drama club, 15 are male.
15 of the 16 members of the drama club are male.

這題的解釋應該是如chris8888說的 兩個俱樂部的人有重複的, 因此不能計算