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**11**on Mon Nov 17, 2014 1:04 pm

# Probability questions

## Re: Probability questions

I think the answer is 6.5

because if the probability of obtaining A is 0.5 and obtaining B is 0.35 and the probability of obtaining neither's intersection is o.2

then 0.5 - 0.2 is 0.3 and 0.35- 0.2 is 0.15

and 0.15 + 0.5 is 0.65 and 0.3+0.35 is also 0.65...................right?

someone please help me this is confusing

because if the probability of obtaining A is 0.5 and obtaining B is 0.35 and the probability of obtaining neither's intersection is o.2

then 0.5 - 0.2 is 0.3 and 0.35- 0.2 is 0.15

and 0.15 + 0.5 is 0.65 and 0.3+0.35 is also 0.65...................right?

someone please help me this is confusing

**Thimodya/Waspinator**- Posts : 10

Points : 10

Join date : 2010-10-03

## Re: Probability questions

I think that it's 0.45.

I did the same thing as Timmy, but instead I added 0.3 to 0.15.

But it could be 0.2.

Neither's intersection is the middle bit, isn't it. So it would be 0.2

So confused

I did the same thing as Timmy, but instead I added 0.3 to 0.15.

But it could be 0.2.

Neither's intersection is the middle bit, isn't it. So it would be 0.2

So confused

**Federico**- Posts : 8

Points : 10

Join date : 2010-10-03

## Re: Probability questions

freddyFederico wrote:I think that it's 0.45.

I did the same thing as Timmy, but instead I added 0.3 to 0.15.

But it could be 0.2.

Neither's intersection is the middle bit, isn't it. So it would be 0.2

So confused

**i**dont

__think__

**A**'∩B' is the

**m**iddle

__se__

**c**ti

**o**n. Mr safdar w

**o**u

**l**dnt give us a question with the answer writen in front of us.

im not too sure if 0.3 to 0.15s wrong though

so i also think its 0.45

the letters in bold give off a truth

**fergus**- Posts : 18

Points : 29

Join date : 2010-10-03

Age : 107

## Re: Probability questions

fergus wrote:freddyFederico wrote:I think that it's 0.45.

I did the same thing as Timmy, but instead I added 0.3 to 0.15.

But it could be 0.2.

Neither's intersection is the middle bit, isn't it. So it would be 0.2

So confusedidontthinkA'∩B' is themiddlesection. Mr safdar wouldnt give us a question with the answer writen in front of us.

im not too sure if 0.3 to 0.15s wrong though

so i also think its 0.45

not bad fergus but thats not a good hidden message and i think that A'∩B' is anything that is not A intersects with anything that is not B so the entire outside of both circles

we want to find where A and B both occur so what we want is the probability of A∩B however where i am having trouble finding that.

the letters in bold give off a truth

**Luka a.k.a GodOfRandom**- Admin
- Posts : 13

Points : 14

Join date : 2010-10-03

## Re: Probability questions

I think the answer is 0.05

because [p(A'∩B') = 0.2] is the probability of obtaining neither's intersection,

and we want to find p(A and B), middle section.

p(A) = 0.5 , p(B) = 0.35 , p(A'∩B') = 0.2 , and I think E = 1

E - p(A'∩B') = p(A∪B)

1 - 0.2 = 0.8 -----------------> so, p(A∪B) = 0.8

p(A∪B) = p(A) + p(B) - p(A∩B)

0.8 = 0.5 + 0.35 - p(A∩B)

∴ p(A∩B) = 0.5 + 0.35 - 0.8 = 0.05

because [p(A'∩B') = 0.2] is the probability of obtaining neither's intersection,

and we want to find p(A and B), middle section.

p(A) = 0.5 , p(B) = 0.35 , p(A'∩B') = 0.2 , and I think E = 1

E - p(A'∩B') = p(A∪B)

1 - 0.2 = 0.8 -----------------> so, p(A∪B) = 0.8

p(A∪B) = p(A) + p(B) - p(A∩B)

0.8 = 0.5 + 0.35 - p(A∩B)

∴ p(A∩B) = 0.5 + 0.35 - 0.8 = 0.05

**Jihye Choi**- Posts : 2

Points : 2

Join date : 2010-10-11

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