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標題: ask a easy probability question [打印本頁]

作者: hinchun34 時間: 4/5/2006 04:36 PM
標題: ask a easy probability question
a choir group has 80 people, they need to choose 20 people for a new group, someone who calls Patrick said he wanted to join with his friend. what is the probability
i haven't learnt it so i don't know whether there is about the structute wrong

作者: JOHNLAM17 時間: 4/5/2006 07:31 PM
I think there isn't enough information.
what is the probability------------> of what?
Patrick said he wanted to join with his friend--------> how many friends?
Is Patick one of the member of choir??

作者: hinchun34 時間: 4/5/2006 08:17 PM

原帖由 JOHNLAM17 於 4/5/2006 19:31 發表
I think there isn't enough information.
what is the probability------------> of what?
Patrick said he wanted to join with his friend--------> how many friends?
Is Patick one of the member ...

how many friend? 1
what is the probility?
i mean u need to find the number
because i haven't learnt it yet
so i don't know how to write it
sorry

作者: sapphire 時間: 4/5/2006 08:40 PM

原帖由 hinchun34 於 4/5/2006 20:17 發表

how many friend? 1
what is the probility?
i mean u need to find the number
because i haven't learnt it yet
so i don't know how to write it
sorry

那是什麼的probability?
是Patrick和他的朋友都被抽中的probability嗎?

作者: hinchun34 時間: 5/5/2006 09:54 AM

原帖由 sapphire 於 4/5/2006 20:40 發表

那是什麼的probability?
是Patrick和他的朋友都被抽中的probability嗎?

yes it is

作者: 細薯 時間: 5/5/2006 02:46 PM

原帖由 kazuhiko 於 5/5/2006 12:52 發表
Requird probability
= (20/80) x (20/80)
= 1/16

not this mei....?

(20/80)(20/80)(4)=1/4

@@

作者: kazuhiko 時間: 5/5/2006 02:54 PM

原帖由細薯於 5/5/2006 14:46 發表

not this mei....?

(20/80)(20/80)(4)=1/4

@@

做咩要乘四？

應該係
Required probobility
= (20/80) x (19/79)
=19/316

[ 本帖最後由 kazuhiko 於 5/5/2006 14:57 編輯 ]

作者: 細薯 時間: 5/5/2006 02:58 PM

原帖由 kazuhiko 於 5/5/2006 14:54 發表

做咩要乘四？

80 ppl -> 4 groups
P(both in group 1) = (1/4)(1/4)=1/16
P(both in group 2) = (1/4)(1/4)=1/16
P(both in group 3) = (1/4)(1/4)=1/16
P(both in group 4) = (1/4)(1/4)=1/16

P(both in the same group) = (1/16)(4)=1/4

correct ma....

原帖由 kazuhiko 於 5/5/2006 14:54 發表

做咩要乘四？

應該係
Required probobility
= (20/80) x (19/79)
=19/316

then.....
(19/316)(4) =0=
i don't know....-__-

[ 本帖最後由細薯於 5/5/2006 15:00 編輯 ]

作者: kazuhiko 時間: 5/5/2006 03:07 PM

原帖由 hinchun34 於 4/5/2006 16:36 發表
a choir group has 80 people, they need to choose 20 people fora new group, someone who calls Patrick said he wanted to join with his friend. what is the probability
i haven't learnt it so i don ...

得一個group 咋嘛

作者: 細薯 時間: 5/5/2006 03:10 PM

原帖由 kazuhiko 於 5/5/2006 15:07 發表

得一個group 咋嘛

ar......i wrongly thought that the 80 ppl form 4 groups of each 20 ppl...==
oic...then that should be 19/316..

作者: hinchun34 時間: 5/5/2006 03:41 PM
yes u ar correct
the answer is told by my teacher
his solution is
78C18
-------
80C20
0.06013(4sig. fig.)

[ 本帖最後由 hinchun34 於 5/5/2006 15:43 編輯 ]

作者: sapphire 時間: 5/5/2006 04:15 PM

原帖由 hinchun34 於 5/5/2006 15:41 發表
yes u ar correct
the answer is told by my teacher
his solution is
78C18
-------
80C20
0.06013(4sig. fig.)

78C18/80C20 的是AL Applied Math的計算方法吧,印象中CE是不能用這方法的......

作者: hinchun34 時間: 5/5/2006 04:27 PM
ok
ic
overall it is taught by my teacher
i don't know it

作者: secret 時間: 5/5/2006 08:58 PM
Mr Patrick:
Why don't you ask your teacher why the problem should be solved in such
an Out-C way? (curious)

作者: hinchun34 時間: 7/5/2006 01:24 PM
because we haven't learnt it yet
and u would know who the teacher is

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