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(edited 3 weeks ago)
Reply 1
Original post by username17263528
https://isaacphysics.org/questions/poisson_quasars?board=155289e6-068a-4217-93da-2bbc92808445&stage=further_a
I am stuck on part d. I tried to find the probability that one of the smaller squares would contain 2 or more quasars, and then raised this to the power 8 to try to get the probability that 8 smaller squares would contain 2 or more quasars. This is evidently the wrong method, so would anyone be able to help? Thank you

Its a fairly standard two part a level stats question where you use the first part to get "p" (so the probability of the small square having at least 2 quasers, or that square "wins"), then you have 16 independent trials and you want at least 8 of them to "win" so what sort of a problem is it?
(edited 1 month ago)
Original post by mqb2766
Its a fairly standard two part a level stats question where you use the first part to get "p" (so the probability of the small square having at least 2 quasers, or that square "wins"), then you have 16 independent trials and you want at least 8 of them to "win" so what sort of a problem is it?

I have tried it out, this is my working: the sum from n=8 to 16 of (16Cn)*(p)^(n)*(1-p)^(16-n) where p is the probability of a small square receiving at least 2 quasars, but don't seem to get the correct answer. to calculate p I calculated P(X=0)+P(X=1)+P(X=2) and then 1-that probability as it is at least 2 quasars, so >=2. If there is a flaw in my working please let me know, help would be greatly appreciated. :smile:
Original post by mqb2766
Its a fairly standard two part a level stats question where you use the first part to get "p" (so the probability of the small square having at least 2 quasers, or that square "wins"), then you have 16 independent trials and you want at least 8 of them to "win" so what sort of a problem is it?

Nervermind, I got it now, my mistake was that I included P(X=2) when trying to calculate the probability of there being at least 2 quasars in a small square.
Original post by mqb2766
Its a fairly standard two part a level stats question where you use the first part to get "p" (so the probability of the small square having at least 2 quasers, or that square "wins"), then you have 16 independent trials and you want at least 8 of them to "win" so what sort of a problem is it?

Hey! I'm stuck on part d of this question https://isaacphysics.org/questions/poisson_woodland?board=343ce8a3-8434-4166-901b-277ec036e4a7&stage=all. I have calculated the probability fo each case, but don't know how to approach it. Maybe multiplying the results together? and the first bit since it says 2 having such number of trees squaring that bit? Any help would be appreciated
Reply 5
Original post by Javier García
Hey! I'm stuck on part d of this question https://isaacphysics.org/questions/poisson_woodland?board=343ce8a3-8434-4166-901b-277ec036e4a7&stage=all. I have calculated the probability fo each case, but don't know how to approach it. Maybe multiplying the results together? and the first bit since it says 2 having such number of trees squaring that bit? Any help would be appreciated

Its best to start a new thread, but you want to find the probability of there being 6 oaks, given that there are at least 6 oaks - so its conditional probability. Then use that probability to get the expected number in 30 areas.
(edited 4 weeks ago)
Original post by mqb2766
Its best to start a new thread, but you want to find the probability of there being 6 oaks, given that there are at least 6 oaks - so its conditional probability. Then use that probability to get the expected number in 30 areas.
Thanks, my mistake was that I did not read the heading correctly, I used lambda for the oaks instead of trees

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