Shoutbox

Whats The chance of you getting something 3 times out of 5

when the chance of getting it each time is 10%

Can you please give me the formula too?

It should be: 1/10*1/10*1/10*9/10*9/10=81/100000

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Originally posted by .Roy
Whats The chance of you getting something 3 times out of 5

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Overall chance of event = 3/5

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Originally posted by .Roy
when the chance of getting it each time is 10%

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Overall chance of event = 1/10

Why do i get the feeling i misinterpreted the question?

Yes you misinterpreted it.
The question in other terms: What is the chance to get it three times on fiveif the chance to get it once = 1/10 ?
So the three times you get it * The two times you won't get it: (1/10*1/10*1/10)*(9/10*9/10)

0.6*0.1? If I am not right I have failed my statistics GCSE last Thursday .

Reload2 has posted the correct answer

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Originally posted by Reload2
Yes you misinterpreted it.
The question in other terms: What is the chance to get it three times on fiveif the chance to get it once = 1/10 ?
So the three times you get it * The two times you won't get it: (1/10*1/10*1/10)*(9/10*9/10)

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But it doesnt make sence, because if you multiply it by (9/10*9/10)

It will lower the chance, and I already know that if you get it 3 times in a row Its (1/10*1/10*1/10) Which SHOULD be a lower percentage then getting it in 3 random points of the draw.

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Originally posted by .Roy
It will lower the chance, and I already know that if you get it 3 times in a row Its (1/10*1/10*1/10) Which SHOULD be a lower percentage then getting it in 3 random points of the draw.

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There's a slight difference though, if i understood your post correctly .
The probability of getting it 3 times in a row is indeed (1/10)^3. BUT, that's considering that you DON'T CARE about what you get in the other 2 tries. So, the probability is, being "A" what you want to get: P(getting A)^3 * P(getting whatever)^2 = (1/10)^3 * 1^2 = (1/10)^3 (Yes, the probability of getting it 3 times in a row or getting it AT LEAST 3 times in random points is exactly the same for that matter ).

Now in the other question they ask you to calculate the probability of getting A 3 times OUT OF 5 (meaning that you have to get EXACTLY 3 times "A", not AT LEAST 3 times. So in the other 2 tries you MUST get, let's say, "B" which will obviously lower the possibility. So the probability is: P(getting A)^3*P(getting B)^2 = (1/10)^3*(9/10)^2

I still aint clear about the question

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Originally posted by John Anderton

I still aint clear about the question

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Then don't post......

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Originally posted by absorbation

0.6*0.1? If I am not right I have failed my statistics GCSE last Thursday .

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I think you failed

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Originally posted by Reload2
It should be: 1/10*1/10*1/10*9/10*9/10=81/100000

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No that is not quite right.... Lets call a success A(1/10) and a failure B(9/10). This equation above would be the probability of AAABB and not the probability of having 3 successes out of 5. You must consider all of the possibilities- AAABB AABAB AABBA ABAAB ABABA ABBAA BAAAB BAABA BABAA BBAAA
There are 10 possible different ways which you can have 3 successes and 2 failures. An easier way to find this number is just by multiplying 5(number of trials) by 2(number of failure/successes, whichever is the smaller number). Each of the 10 possible outcomes above all have the same probability of occuring and that probability is 1/10*1/10*1/10*9/10*9/10=81/100000 so 81/100000*10= 81/10000 or .81% chance

The formula would be...
(probability of successes^number of successes)*(probablility of failure^number of failures)*number of trials*(number of failure/successes, whichever is the smaller number)

* Grue hopes he is remembering his statistics right