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 October 13th, 2013, 03:18 PM #1 Senior Member   Joined: Oct 2009 Posts: 895 Thanks: 1 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
 October 13th, 2013, 04:48 PM #2 Global Moderator     Joined: Oct 2008 From: London, Ontario, Canada - The Forest City Posts: 7,958 Thanks: 1146 Math Focus: Elementary mathematics and beyond 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.
 October 14th, 2013, 02:22 AM #3 Senior Member   Joined: Oct 2009 Posts: 895 Thanks: 1 Re: questions in probability Thanks, but in question number two, for 2, 3 and 4, can explain to me how you got that?
 October 14th, 2013, 04:07 AM #4 Global Moderator   Joined: Dec 2006 Posts: 20,926 Thanks: 2205 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.
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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 2 dice grid.JPG (27.1 KB, 65 views)

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# Rachel bought a CD which is her favourite track, 8 other tracks

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