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question 27 (2 Viewers)

connie

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(b) (i) 25/26 ?
(ii) lose 20 cents



did u get this?
 

Dammit

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your answer for ii depends on what you thought i was.

Sooooooo....there are two ways you could've done b) i.

What is the probability that neither shows a 6.

You could look at it this way:
there are 6 sides to a dice, so you have 5 out of 6 chance of not rolling a 6.

so it would be 5/6 * 5/6
= 25/36 ( i think thats what you meant to type......

BUT, that doesnt necessarily work cos ONE of the dice may turn to 6

So you have to work out:
P(6,6)= 1/6 * 1/6
= 1/36

So THEREFORE probability NEITHER is a 6 is 35/36.

Then,

ii)
1/36 * $20
1/6 * $2
35/36 * -$2
= -$1.06

so i dunno, this could be the answer or it could not :(

Comments please.
 

connie

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hmmm yep i think your right! there goes another couple of marks... g i don't understand how i could screw up so badly!
 

connie

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actually my probabilities might have been right, if you draw a tree diagram? i got

p(6,6) = 1/36
p(?, 6) = 11/36
p(no 6) = 25/36
 

Chat1

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I got
1/36 chance of making $20
5/36 chance of making $2
25/36 chance of losing $2

which means you will lose 56 cents


Dammit: to win $2.00 probabilty of getting a 6 is more then 1/6 because you role 2 dice, which will increase your chance.
 
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connie

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but we are talking about different things? so the probability didn't have to add up to 1? there is more then 5 in 36 chance of getting one 6!!!

1,6 2,6 3,6 4,6 5,6 6,1 6,2 ,6,3, 6,4 6,5 which is 10/36? oops so my 11 was one off! damn

but 1/36 + 10/36 + 25/36 = 36/36 or 1?!!!

yours don't add up so i think i've got the answer
 

connie

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so the you just had to x each one by the amount of money? and you will get the answer... hmm.. i don't think im the only one who went bad now!
 

Gregor Samsa

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Originally posted by Chat1
I got
1/36 chance of making $20
5/36 chance of making $2
25/36 chance of losing $2

which means you will lose 56 cents


Dammit: to win $2.00 probabilty of getting a 6 is more then 1/6 because you role 2 dice, which will increase your chance.
I got the same answers, so hopefully it isn't incorrect. :p
 

Chat1

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Yeah urs looks right

I knew they had to add up to 1. In the exam i knew it too. But instead i did 1/6 * 5/6. I'm pretty sure thats wrong tho.
Fuck!!
 

connie

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lol but don't u feel better knowing we all screwed up together? lol i do? is dammit still sure about 92? i've worked out i got 86.5! yeh and i was aiming for 100!
 

Inca

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Screw it! I shouldve just lived in blissful ignorance and not come to look at this board.
Dont you hate it when you do the right thing first, and then scribble it out and do the wrong thing?
...CRAP!
 

Dammit

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connie: when i marked my paper i realised i got it wrong and gave myself 0 for i) and 2 for ii
 

Chat1

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I make sure i dont take any of my exam papers from the hall. I dont wanna be going over them and finding out everything i got wrong.
 
M

mushi

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ok i got -0.27

to win $20 -( 1/6 x 1/6*20 = 1/36
to win 2, it is ( 1/6 x 5/6*2 ) + ( 5/6 X 1/6 ) = 10/36 ( since u can get a 6 on the first try , and a 6 on a second try, therefore 2 ways..if u get what i mean

to lose $2 (5/6 x 5/6*-2 ) = 25/36

then do the right calculations u get -0.27..

hope its right :p
 
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Dammit

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mushi but read above about the last to lose $2 (5/6 x 5/6*-2 ) = 25/36

its not 25/36 its 35/36......
 

KAty

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hey mushi and hollie i got the same as you -$0.28
i hope its right every0one is saying something different do u think we did it right
i was pretty confident with this question and it was work 3 marks !
 

honky tonk

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Originally posted by Dammit
its not 25/36 its 35/36......
I might be misreading the question, but didn't it ask for neither die showing a 6? Doesn't that mean that there are 11 chances out of 36 that at least one will show a 6? Have a look:

6, 1
6, 2
6, 3
6, 4
6, 5
6, 6
1, 6
2, 6
3, 6
4, 6
5, 6

Total of 11

36 - 11 = 25

25/36?
 

honky tonk

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Originally posted by Chat1
which means you will lose 56 cents
*LoL* I got that too, so we're in the same boat at least. :p

Originally posted by connie
lol but don't u feel better knowing we all screwed up together? lol i do? is dammit still sure about 92? i've worked out i got 86.5! yeh and i was aiming for 100!
I've calculated an 83.. a bit lower than I was hoping, but i'm still semi-satisfied. :)
 

hereSIR

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Pretty sure (about this one i.e Prabability(sure)=35/36)) that:

Answers
are
P(66) = 1/36
P(one six) = 5/18
P(neither 6) = 25/36
Which gives the financial Expectation = -0.2777777 = -$0.28
 

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