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Dice question (1 Viewer)

lilkiwifruit

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This is a really stupid question which i can't work out...
A die is thrown 3 times what is the probability of throwing at least 2 sixes?
 

lilkiwifruit

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*sinks to knees in despair* this is one of those easy questions that bugs you if u cant answer it ...
 

kami

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1/5kiwifruit said:
This is a really stupid question which i can't work out...
A die is thrown 3 times what is the probability of throwing at least 2 sixes?
First throw: 1/6
Second throw: 1/6
Third throw: 5/6(remember there are five other options besides 6)
then just multiply each throw's chance and thats the answer.
 

kami

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but the answer is 16/216...not 5/216 ...im so confused
oh crud, I've messed you up lol, sorry didnt read the "at least" so you add the possibility of the two sixes with the possibility of three sixes.
 

webby234

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kami said:
First throw: 1/6
Second throw: 1/6
Third throw: 5/6(remember there are five other options besides 6)
then just multiply each throw's chance and thats the answer.
You need to multiply by 3 as there are 3 different ways of getting 2 sixes.

So 3*1/6*1/6*5/6 = 15/216

+ (1/6)^3 = 16/216
 

ephemeral

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Pr(atleast 2 sixes)= Pr(2 sixes)+Pr(3 sixes)

Using Binomial Distribution

Pr(2 sixes)= 3C2(1/6)^2(5/6) = 5/72
Pr(3 sixes)= 3C3(1/6)^3 = 1/216

(5/72)+(1/216)= 2/27 = 16/216 as required.
 

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