Probability - Paper Problem

lindah · 2010-02-05 09:32:16

Hi all,

May I obtain any hints, tips, feedback for this question please!?!
Thank you in advance!!

There are four sheets of paper.
The first has Thai writing on one side, and an English translation on the other.
The second has Chinese writing on one side, and an English translation on the other.
The third has Korean writing on one side, and an English translation on the other.
The fourth has English writing on one side, and English on the other.
I randomly choose a sheet of paper and put in front of you, if it is English, what is the probability of the other side being English?

I am treating each side as 1 so there is a 5/8 chance of randomly picking the English side.
There is a 1/4 chance of picking the paper with English on both sides.

So using conditional probability : 1/4 divided by 5/8 = 2/5
Or is it simply 1/4? I tend to over think and confuse myself

John E. Franklin · 2010-02-05 10:35:15

I'm not 100% sure, but I think the answer is 2/5 or 40% chance of turning over and getting English.
The way I see it is there are 8 sides of paper:
Th <--> E1
Ch <--> E2
K <--> E3
E4 <--> E5
And if you choose an E to start, then note
that E1 --> Th
E2--> Ch
E3 --> K
E4 --> E5
and
E5 --> E4
So E --> E 2 times out of 5.
Answer not 100% guaranteed.

Last edited by John E. Franklin (2010-02-05 10:37:35)

lindah · 2010-02-06 06:40:47

Thanks for your assistance!!!

I had the same line of thinking, therefore thought it couldn't be 1/4.

John E. Franklin · 2010-02-06 06:48:02

Yeah, I hope we're right !

soroban · 2010-02-06 06:58:13

.

There are four sheets of paper.
The first has Thai writing on one side and English on the other.
The second has Chinese writing on one side and English on the other.
The third has Korean writing on one side and English on the other.
The fourth has English writing on one side and English on the other.
I randomly choose a sheet of paper and put in front of you.
If it is English, what is the probability of the other side being English?

. .

.

John E. Franklin · 2010-02-06 07:23:20

@soroban,
don't you want "visible" and "hidden" to be switched on your chart ?

Math Is Fun Forum

#1 2010-02-05 09:32:16

Probability - Paper Problem

#2 2010-02-05 10:35:15

Re: Probability - Paper Problem

#3 2010-02-06 06:40:47

Re: Probability - Paper Problem

#4 2010-02-06 06:48:02

Re: Probability - Paper Problem

#5 2010-02-06 06:58:13

Re: Probability - Paper Problem

#6 2010-02-06 07:23:20

Re: Probability - Paper Problem

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