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October 13th, 2013, 03:18 PM   #1
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questions in probability

Question 10
Rachel buys a new CD, on which is her favourite track, 8 other tracks she likes and 2 tracks that she does not like.
She sets her CD player to play at random.
What is the probability that the first track it plays is:
(a) Rachel's favourite


(b) a track that she likes


(c) a track that she does not like

[color=#800000]my answer

a) 8/10
b) 8/10
C) 2/10[/color]


-------------------------
Q2 :

Two fair dice are rolled at the same time. What is the
probability that the total score is
1) 6
2) greater than 9
3) less than 7
4) that is an even number
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October 13th, 2013, 04:48 PM   #2
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Re: questions in probability

Question 10: 1 + 8 + 2 = 11.

Q2: 1) The number of possible outcomes is 36. Possible outcomes where both dies total 6 are (1, 5), (2, 4), (3, 3), (4, 2), (5, 1). The probability that the dice total 6 is 5/36.
2) 1/6.
3) 15/36.
4) 1/2.
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October 14th, 2013, 02:22 AM   #3
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Re: questions in probability

Thanks, but in question number two, for 2, 3 and 4,

can explain to me how you got that?
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October 14th, 2013, 04:07 AM   #4
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It's just a matter of counting the possibilities. If, for example, the total score is greater than nine (i.e., 10 or more), there are six possibilities: (4,6), (5,5), (5,6), (6,4), (6,5), and (6,6). Hence the required probability is 6/36 = 1/6.
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October 14th, 2013, 04:46 AM   #5
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Re: questions in probability

1a) 1/11
b) 9/11
c) 2/11

Q2 Draw a grid like this one
The first die is horizontal the second is vertical. There are 36 possible combinations. Remember (1,2) is different from (2,1).
Then you can just tick off the favourable boxes (I already put the additions in the boxes)

a) 5/36, b) 6/36 c) 15/36, d) 18/36 just as Greg said.

[attachment=0:1nxkdesg]2 dice grid.JPG[/attachment:1nxkdesg]
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File Type: jpg 2 dice grid.JPG (27.1 KB, 65 views)
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