probability question helpWatch

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#1
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.

Thanks
0
6 years ago
#2
(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.

Thanks
What have you tried
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#3
(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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#4
(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
0
6 years ago
#5
(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
0
6 years ago
#6
(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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#7
i really dont know thats why im asking on here...
0
6 years ago
#8
don't you have to do some tree diagram to work it out first?
0
6 years ago
#9
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

1
#10
so for i got

1. 0.721

2. 0.763

are these answers the same as what you guys got?
0
6 years ago
#11
i gave up... my brain dont work... wait a moment let me try again.....
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6 years ago
#12
sorry cant do it.... i think im over complicating it for myself
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6 years ago
#13
?
(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
0
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