candyloveee
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how would i do these two questions?

1. What is the probability of rolling AT LEAST one six in 7 rolls of a FAIR die.

2. you sample five fish from an lake where one in four fish carry a parasite, what is the probability that you will sample at least one parasitized fish? Assume that the population is so large that you are effectively sampling with replacement.

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TenOfThem
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(Original post by candyloveee)
how would i do these two questions?

1. What is the probability of rolling AT LEAST one six in 7 rolls of a FAIR die.

2. you sample five fish from an lake where one in four fish carry a parasite, what is the probability that you will sample at least one parasitized fish? Assume that the population is so large that you are effectively sampling with replacement.

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What have you tried
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candyloveee
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(Original post by TenOfThem)
What have you tried
i thought itd just be 1/6 * 7 for the first one..but that seems too easy to be right
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candyloveee
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(Original post by TenOfThem)
What have you tried
and for the fish one, 1/4 * 5 . but again..i dont have the answers, so dont know whats right or wrong
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TenOfThem
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(Original post by candyloveee)
i thought itd just be 1/6 * 7 for the first one..but that seems too easy to be right
given 7/6>1 that cannot possibly be correct can it?


Work out the probability that NONE of the dice has a 6
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TenOfThem
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(Original post by candyloveee)
and for the fish one, 1/4 * 5 . but again..i dont have the answers, so dont know whats right or wrong
And, again, since 5/4>1 that is not possible
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candyloveee
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i really dont know thats why im asking on here...
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Giggles Shocker
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don't you have to do some tree diagram to work it out first?
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trouducul
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prob to obtain a 6: 1/6
prob not to obtain a 6: 1- 1/6 = 5/6
prob not to obtain a 6 in 7 rolls5/6)^7
prob to obtain at least a 6 in 7 rolls: 1-
(5/6)^7

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candyloveee
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so for i got

1. 0.721

2. 0.763

are these answers the same as what you guys got?
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Giggles Shocker
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i gave up... my brain dont work... wait a moment let me try again.....
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Giggles Shocker
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sorry cant do it.... i think im over complicating it for myself
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trouducul
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(Original post by Giggles Shocker)
sorry cant do it.... i think im over complicating it for myself
It's exactly the same procedure as in the first one.

prob that a fish has a parasite: 1/4
prob that a fish does not have a ***** parasite: 1- (1/4) = 3/4
prob that the 5 fish do not have parasite: (3/4)^5
prob that at least one of them has: 1-
(3/4)^5
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