help me pls... stucking on this problem..
even im not sure whether it is permutation or combination...tq.
Three identical slips of paper with the number 1,2,3 are placed in a box.One slip is randomly selected and then without replacement, a second slip is selected.Find the probability that the sum of the two number is even...

Question

help me pls... stucking on this problem..
even im not sure whether it is permutation or combination...tq.
Three identical slips of paper with the number 1,2,3  are placed in a  box.One slip is randomly selected and then without replacement, a second slip  is selected.Find the probability that the sum of the two number is even...

anonymous · Answer

anybody ??

anonymous · Answer

You have 3 numbers.

You have to pick 2 of them.

You could pick (12=odd), (13=even) or (23=odd)

anonymous · Answer

only 13 will give even number. so...

anonymous · Answer

Correct.

Only 1 combination out of 3 possible combinations.

kirbykirby · Answer

but 1st paper = 1, 2nd paper =3 is not the same as 1st paper =3, 2nd papper = 2

kirbykirby · Answer

so there are 2 possibilities

anonymous · Answer

Wut???

kirbykirby · Answer

(1,3) and (3,1) are nt the same here, because you pick the different paper on different turns

anonymous · Answer

Yes they are the same.

If you must pick 2 numbers out of 3, the odds of their sum being even is 1:3

This is because "order doesn't matter".

And even if order DID matter, then you still have 2 possibilities out of 6 that the sum is even - which is STILL 1:3.

kirbykirby · Answer

ok
but probability are written as 1/3

kirbykirby · Answer

1:3 is a ratio and doesn't mean 1/3

anonymous · Answer

Yes it does.

the ratio 1:3 is mathematically indistinguishable from the fraction 1/3

whpalmer4 · Answer

odds and probability are not the same! see for example http://mathworld.wolfram.com/Odds.html

kirbykirby · Answer

Ok I was reading online and apparently the notation : is sometimes used to mean "odds" which is different from "ratio" (which is equivalent to a fraction), from what I gathered. I always used the colon : for 'odds'

whpalmer4 · Answer

I was surprised to discover the difference as well, and noted with dismay how sloppy I've been with terminology in the past in this regard.  @qweqwe123123123123111 take note!

anonymous · Answer

The OP asked for the probability that any draw of 2 numbers out of the 3 would be even.

Technically, the "probability" of that happening is 33.33333...%, while I expressed the answer as odds.
33.3333....% expressed as a fraction is 1/3
33.3333....% expressed as odds 1:3
33.3333....% expressed as a decimal is .333333....

Split a pie into 3 even pieces, and each piece is 1/3 of the pie. The ratio of 1 piece to the whole pie is 1:3. Each piece is 33 1/3% of the pie.

Changing a ":" into a "/" or moving a decimal point to make way for a "%" is not rocket science, folks. It's all the same thing.

whpalmer4 · Answer

yes, but you interchangeably refer to "odds" and "probability" and they are NOT the same.

kirbykirby · Answer

it's just that "odds" and "ratio"(or probability, or fraction) can use the same notation of a colon, but they mean different things. And I'm sorry for the confusion perhaps. I learnt the "odds" in the french system where they called it "ratio" but it doesn't translate the same in english

whpalmer4 · Answer

odds and probability are different.  did you read the article?

kirbykirby · Answer

if u write 1:3... as a ratio it means 1/3
1:3 as an odds would be like 1/4

anonymous · Answer

It translates just fine.

There is no mathematical difference whatsoever between a ratio of 1:3, the odds of 1:3 or the probability of 1/3.

None. 

The ONLY "error" I made was that the OP asked for the probability (which would be expressed as 1/3 or 33% or whatever), and I expressed them as odds.

kirbykirby · Answer

u didn't read the wolfram article did you ._.

anonymous · Answer

kirbykirby: "if u write 1:3... as a ratio it means 1/3; 1:3 as an odds would be like 1/4"

WTF?????

How in everloving hell do you manage to conjure 1/4 out of 1:3 ????????????????????

kirbykirby · Answer

1/(3+1) ... the wolfram article says if you have an ODDs r:s, then the probability is r/(s+r)

kirbykirby · Answer

But I was just confused about the word "ratio", because in the french system we used "ratio" to mean "odds", but that isn't the case in english.

anonymous · Answer

Okay, I concede that "odds" are in fact different from "probability". Now don't get all excited at that, because there still is no difference at all between 1:3, 1/3 or 33 1/3% My error was in the terminology, not the math. Now, to answer the OP's question: The PROBABILITY of your selection summing evenly is 1/3 That is what the OP asked for, and this may be expressed as 33.3333%, 33 1/3%, .33333..., or 1:3 Now let's address what the ODDS are: The ODDS of his selection summing evenly are 1:2 This page is much clearer than wolfram's: http://www.math-magic.com/probability/prob_to_odds.htm

kirbykirby · Answer

oh i am not denying that 1/3 is the correct answer, which is a probability. I was just confused by the term "ratio".

kirbykirby · Answer

I probably should have no said anything in this post.. lol

whpalmer4 · Answer

No one is excited by your concession.  We're just trying to get everyone to agree on the terminology.  My only concern with your statement that caused me to speak up was that you used the mistaken terminology (and as I said, you are neither the first nor the last to make this particular mistake — I've been doing it for years!)  I think the French language angle on this issue is interesting...

anonymous · Answer

Okay, well done!  :-)

kirbykirby · Answer

Yes! =]

anonymous · Answer

thanks a lot !best response for all of you  !!!