Hailwood Posted April 20, 2010 Share Posted April 20, 2010 so guys, im making an application and i need to know how to solve a problem such as below. can someone please solve this and post how to do so, or even just how to do so. Cheers. it is literally the maths i am stuck on. extracting the relevant parts i have done. 12% of voters in a recent election voted on the greens candidate, if 10 people were randomly selected what is the probability that exactly 4 people voted for the green candidate. Link to comment https://forums.phpfreaks.com/topic/199140-not-strictly-a-php-problem/ Share on other sites More sharing options...
cs.punk Posted April 20, 2010 Share Posted April 20, 2010 -------------- Er sorry read your question wrong. Link to comment https://forums.phpfreaks.com/topic/199140-not-strictly-a-php-problem/#findComment-1045226 Share on other sites More sharing options...
Ken2k7 Posted April 20, 2010 Share Posted April 20, 2010 Is it 2% ? Link to comment https://forums.phpfreaks.com/topic/199140-not-strictly-a-php-problem/#findComment-1045241 Share on other sites More sharing options...
cs.punk Posted April 20, 2010 Share Posted April 20, 2010 A more logical view: 10 blues in a bag of 100. take ten, the chance would be 1 out of ten for being blue. for 2 blues it would be a 0.5 chance.. 4 blues would be 0.25. SO..: 12 A(s) in 100. 1.2 A(s) in 10. / 4 = 0.3 in 10. Sorry this is doing my head in.. ? You just divide the chance... Hmmm I should pay more attention to math. Link to comment https://forums.phpfreaks.com/topic/199140-not-strictly-a-php-problem/#findComment-1045285 Share on other sites More sharing options...
Ken2k7 Posted April 20, 2010 Share Posted April 20, 2010 It's really a simple math, that is, if I understand it correctly. 12% of voters vote green 10 people Find P(exactly 4) Exactly 4 = 4 vote green, 6 vote others So, X ~ Binomial(10, 4). 4 with probability .12 and 6 with probability .88. From that, we have this - [tex]\binom {10} {4}\cdot(.12)^4\cdot(.88)^6 = .02 = 2\%[/tex] Link to comment https://forums.phpfreaks.com/topic/199140-not-strictly-a-php-problem/#findComment-1045298 Share on other sites More sharing options...
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