If there were 5 red octopuses in the ocean, 7 purple octopuses and 9 orange octopuses, what is the probability that you'd see 3 orange octopuses? :confused: help!! I need to know this answer tonight please!

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Originally Posted by Kaykay09

If there were 5 red octopuses in the ocean, 7 purple octopuses and 9 orange octopuses, what is the probability that you'd see 3 orange octopuses??:confused: help!!! i need to know this answer tonight please!!

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Do you mean what are the odds of spotting 3 orange ones in a row, out of 3 tries?

No.. altogether in my question there are 21 total octopuses. And there are 9 orange ones. What's the chance we're going to see 3 of those orange ones?

Would it be 9 out of 21?

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Originally Posted by Kaykay09

No..altogether in my question there are 21 total octopuses. and there are 9 orange ones. whats the chance we're gunna see 3 of those orange ones?

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I understand that :o, however I am asking what is the number of octopi you can see. You may want to find 3 orange ones, but is 3 the maximum amount, or perhaps is it 5? Or 6 octopi?

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Originally Posted by Nhatkiem

I understand that :o, however I am asking what is the number of octopi you can see. you may want to find 3 orange ones, but is 3 the maximum amount, or perhaps is it 5? or 6 octopi?

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The max number is 21

Hahah, no no, I think you are misunderstanding me. For example, I have 10 red marbles, 6 blue marbles. I want at least 2 blue marbles, but I can pick up to 4.

I'm asking how many your allowed to pick, not just what you want to pick.

you're allowed to pick 9 because there's 9 orange ones haha I think I'm sorry if I'm confusing I'm new at all this probability stuff :p

Ahh well if your new then its probably not what I'm thinking of.

If your looking for just the probability of spotting 3 orange octopi in a row, it would be the probability of the spotting the first one times the probability of spotting the second one... etc.

so you're probability would be
let O represent the number of orange octopi, and N represent total octopi

probability =

Sorry that "a" should be a "1" in the (N-a), must have miss punched a key..

Yeah haha. Oh okay... yeah! Okay! Thank you for your help!

Yeah haha. Oooo ohh okay.. yeah! Well thank you very very much for your help!

I think the question was seeing the octopi altogether, which brings it to 9/21 * 8/20 * 7/19. I don't have a calculator with me :o

Thanks jerry! That made a lot of sense! And that's true haha

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Originally Posted by Unknown008

I think the question was seeing the octopi altogether, which brings it to 9/21 * 8/20 * 7/19. I don't have a calculator with me :o

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That's equivalent to my :p

Oh sorry, I thought you were posting another binomial expansion again :o

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Originally Posted by Unknown008

Oh sorry, I thought you were posting another binomial expansion again :o

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HAHAHA, I'd figured after a page of asking her that it probably wasn't binomial expansion :D

Which is equivalent to (9C3) over (21C3) on a calculator.

Yeah but calculators are no fun :p

LOL, you are right, garbage in, garbage out