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Binomial/ Poisson distribution

X~Bin(12,0.15), what's the probability X is greater than or equal to 2. I've tried this question again since my test and got 0.292, is this right?(12C2)(0.15^2)(0.85^10).
(edited 5 years ago)
Original post by Bameron
X~Bin(12,0.15), what's the probability X is greater than or equal to 2. I've tried this question again since my test and got 0.292, is this right?(12C2)(0.15^2)(0.85^10).
That's the probability that X = 2, surely?

Also this question, it's a bit foggy in my memory but I hope it's correct: Find the mean of X~Poi(6) for 4 less than or equal to X < 6. This one I don't know what to do, a starting hint would be lovely.
This doesn't look right. I could guess what you mean, but that's just a waste of my time frankly. The onus is on you to put in the time and effort to state the question correctly.
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Bameron
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Original post by DFranklin
That's the probability that X = 2, surely?

This doesn't look right. I could guess what you mean, but that's just a waste of my time frankly. The onus is on you to put in the time and effort to state the question correctly.

Ok sorry about the second part.

Having another stab at the binomial one.

Could I do 1 - (P(X=0) + P(X=1) + P(X=2))? I think this would give 0.264.
Original post by Bameron
Ok sorry about the second part.

Having another stab at the binomial one.

Could I do 1 - (P(X=0) + P(X=1) + P(X=2))? I think this would give 0.264.

No, that would give the probabiltity of X being greater than 2, not greater than or equal to 2, as you said earlier.

Other than that, it's the right approach.
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Bameron
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Original post by DFranklin
No, that would give the probabiltity of X being greater than 2, not greater than or equal to 2, as you said earlier.

Other than that, it's the right approach.

Bleh, please put me out of my misery, I need to move onto some continous random variables practice.

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