Hi, R-help is not a homework help list. If you're having trouble, you need to speak with your instructor instead.
Best of luck, Sarah On Tue, May 15, 2012 at 8:04 AM, Eva-Lotta Blom <[email protected]> wrote: > > 1. Emma is performing an experiment that requires individual handling of > some animals. The sizes of the animals are lognormally distributed: The > natural logarithms of their sizes has a normal distribution with mean 3 and > standard deviation 0.4. The time (in minutes) it takes to handle each animal > is given by > > 10 + s · 1.5 + eε for animals with s ≤ 20 20 + s · 0.8 + eε for animals with > s > 20 > > where ε is a random variable that is normally distributed with expectation 1 > and variance 0.3. > > For a randomly picked animal, what is the (approximate) probability that it > can be handled in less than 30 minutes? > > We can solve this exercise using simulation, as follows: Simulate a vector S > with the sizes of 10000 animals, by using the rnorm function and the “exp” > function. Then, compute a vector Time of length 10000 with the times it takes > to handle each of these 10000 animals: Remember that to separate between the > two cases, you can use notation like for example “Time[S < 20]”. The random > component eε can be added by combining the “exp” function with the “rnorm” > function. Finally, you can find the proportion of simulated values below 30. > Re-do the computations a couple of times to get an idea of the variability of > the result. > > s <- c(10000) > S <- exp(rnorm(s, 3, 0.4)) [1]# vector 10000, mean, sd > Time <- 10+S*1.5 [1] # 10 + s · 1.5 + eε for animals with s ≤ 20 > time <- 20+S*0.8 [1] # 20 + s · 0.8 + eε for animals with s > 20 > > can't get any further and i can't really find a good help page to solve the > code. > can you help me? > Lotta > > ------------------------------------------------------------------------------------ > Eva-Lotta Blom PhD student > Dept. of BioEnv . Tjärnö > University of Gothenburg > 452 96 Strömstad > Sweden > > > > > > > > [[alternative HTML version deleted]] > > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > -- Sarah Goslee http://www.stringpage.com http://www.sarahgoslee.com http://www.functionaldiversity.org ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
