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You are not logged in. #1 20130413 23:00:46
xpected valueA school is running a raffle for two prizes. 59 tickets were sold for the raffle, numbered 1,…,59. All the tickets are put into a hat and a teacher picks out two tickets which have numbers i and j from the hat. What is the expected value of i−j? 'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.' 'God exists because Mathematics is consistent, and the devil exists because we cannot prove it' 'Who are you to judge everything?' Alokananda #3 20130413 23:28:26
Re: xpected valueI am getting 20 'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.' 'God exists because Mathematics is consistent, and the devil exists because we cannot prove it' 'Who are you to judge everything?' Alokananda #5 20130413 23:40:55
Re: xpected valueI am getting 20 as well. The limit operator is just an excuse for doing something you know you can't. “It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman “Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment #6 20130413 23:43:49
Re: xpected valueIf there picking without replacement then the answer is 20. If not the answer in post #2 holds. In mathematics, you don't understand things. You just get used to them. I have the result, but I do not yet know how to get it. All physicists, and a good many quite respectable mathematicians are contemptuous about proof. #7 20130413 23:46:10
Re: xpected value"The teacher picks out two tickets" The limit operator is just an excuse for doing something you know you can't. “It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman “Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment #8 20130413 23:50:13
Re: xpected valueThat does suggest without replacement. The answer is (59 + 1 ) / 3 = 20. In mathematics, you don't understand things. You just get used to them. I have the result, but I do not yet know how to get it. All physicists, and a good many quite respectable mathematicians are contemptuous about proof. #9 20130413 23:52:17
Re: xpected valueExplain in simple words please 'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.' 'God exists because Mathematics is consistent, and the devil exists because we cannot prove it' 'Who are you to judge everything?' Alokananda #10 20130413 23:56:48
Re: xpected valueHi; ways. The standard way now to do this is to look at the ordered pairs. There is 1 way for 2 to be the maximum and 2 ways for 3 to be the maximum and there are generally m1 ways for m to be the maximum. Using the formula for expected value or expected number: For the second part, you do it in the same way. There are still n (n1)/2 ways to arrange n numbers with high and low. Now you go through the numbers in the same way. 1 is the lowest n1 times. 2 is the lowest n  2 times. n can never be the lowest. n1 is the lowest one time so generally m is lowest n  m times. We use the same formula for expected value: Now for the difference. Just subtract the expected value of the lowest from the highest. The absolute value is implied in there. When you have time please sign up over here: https://brilliant.org/ In mathematics, you don't understand things. You just get used to them. I have the result, but I do not yet know how to get it. All physicists, and a good many quite respectable mathematicians are contemptuous about proof. #11 20130415 23:31:27
Re: xpected value
Hi, and for any n "Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  Buddha? "Data! Data! Data!" he cried impatiently. "I can't make bricks without clay." #12 20130415 23:46:16
Re: xpected valueHmm, and the rows are obtained how? 'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.' 'God exists because Mathematics is consistent, and the devil exists because we cannot prove it' 'Who are you to judge everything?' Alokananda #13 20130415 23:53:04
Re: xpected valueStart with the first two numbers and end with the last two, listing each combination. "Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  Buddha? "Data! Data! Data!" he cried impatiently. "I can't make bricks without clay." #14 20130416 00:07:50
Re: xpected valuegOt it Last edited by Agnishom (20130416 00:08:24) 'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.' 'God exists because Mathematics is consistent, and the devil exists because we cannot prove it' 'Who are you to judge everything?' Alokananda 