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Topic: Math help. (Read 379 times)

member
Activity: 84
Merit: 10
January 27, 2014, 03:23:40 AM
#7
this isnt my level Grin
hero member
Activity: 955
Merit: 1002
January 27, 2014, 02:09:44 AM
#6
It's a binomial distribution

p=0.8, 5 indicators
X is number of indicators that are active

for majority active
Pr(X>2)=Pr(X=3) + Pr(X=4) + Pr(X=5)


boils down to: 10(0.8 )^3(0.2 )^2 + 5(0.8 )^4(0.2) + (0.8 )^5
=0.94208





http://en.wikipedia.org/wiki/Binomial_distribution

edit: someone beat me to it
newbie
Activity: 40
Merit: 0
January 27, 2014, 02:08:04 AM
#5
Oh cool, thanks.

That makes sense.
newbie
Activity: 40
Merit: 0
January 27, 2014, 02:02:48 AM
#4
Lets say you have a certain number of indicators. Each indicator on it's own own has an 80% chance of being accurate, if you have 5 or 7 different indicators say, how likely is it that the majority would be accurate ?

Thanks.

Overall the majority will be accurate - you have said 80% will be accurate, and 80% is a majority.

Sorry, to clarify, I mean each indicator on it's own is 80% accurate.

Lets say we have 5 indicators that each will say "red" 80% of the time to indicate red, but can also sometimes say "blue" 20% of the time.

What are the chances of 3/5 of them saying "red", what are the chances of all of them saying "blue" ? etc.
newbie
Activity: 40
Merit: 0
January 27, 2014, 01:47:13 AM
#3
5 * 0.8 = 4

How does that tell me what I'm asking ?
legendary
Activity: 947
Merit: 1042
Hamster ate my bitcoin
January 27, 2014, 01:35:40 AM
#2
5 * 0.8 = 4
newbie
Activity: 40
Merit: 0
January 27, 2014, 01:27:46 AM
#1
Lets say you have a certain number of indicators. Each indicator on it's own own has an 80% chance of being accurate, if you have 5 or 7 different indicators say, how likely is it that the majority would be accurate ?

Thanks.
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