document.write( "Question 1158324: Hi Professor:\r
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document.write( "I have a question related to the probability, a stock price is currently at $10, what will be the probability the stock price will be above $10 after 5 days? Assume the stock price will be randomly moved according to the following exact percentages: -3%, -2%, -1%, 1%, 2% and 3% (so there are total 6 different possible percentages movement and the movement are purely random among each day). \r
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document.write( "My approach to this problem is the following: there are total 6 different movement, and the total trials are 5 days, so the total permutations will be 6^5=7776, but I just can't continue the rest due to my limited math knowledge, could you help me out on this?\r
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document.write( "Thank you for reading my email and I am looking forward to hearing from you soon. \r
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document.write( "Alex
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document.write( "California\r
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document.write( "Hi Tutors:\r
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document.write( "Thank you for answering my questions above (at Answer 781251 ). \r
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document.write( "I think the answer (781251) just solved one of the permutation, what if the percentage change were repeatable negative percentages, these percentage changes are all independent, so it could have like: -3% every single days, or -3% for 3 days then another 2 days -2%, etc. I wanted to know what are the probability under all the permutations, what are the chances that the stock price at the end of 5th day will be above $10?\r
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document.write( "again, thanks
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document.write( "Alex \n" );
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Algebra.Com's Answer #781245 by greenestamps(13200)![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "original response deleted... I'm looking at this further.... \n" ); document.write( "---------------------------------------------------------------------- \n" ); document.write( "In my earlier attempt at solving this, I tried to simplify the problem by treating all the percent increases and decreases as being relative to the original price. That way, for instance, increases of 3% and 3% would exactly balance decreases of 1%, 2%, and 3%. \n" ); document.write( "However, that is probably not how the problem was intended. \n" ); document.write( "If the percentage increases or decreases are treated as multipliers, there is NO permutation of 5 of the 6 posssible percentage changes that results in an ending price exactly equal to the starting price. \n" ); document.write( "So I looked at the problem again.... \n" ); document.write( "Certainly the other tutor missed the point of the problem, finding the percent increase or decrease if each of the changes is applied once. \n" ); document.write( "It appears to me that a purely analytic solution would be extremely tedious, making it necessary to examine each permutation of 5 of the 6 percentage changes. \n" ); document.write( "So I built an excel spreadsheet with all 6^5=7776 permutations of 5 of the 6 and identified the ones that produced a product greater than 1. \n" ); document.write( "ANSWER: 3588 of the 7776 permutations of 5 of the 6 percentage changes produce a product greater than 1. Therefore, the probability that the stock price will be above the original $10 after 5 days is 3588/7776, or about 46.142%. \n" ); document.write( " \n" ); document.write( " |