Command qchisq returns the value of chi square distribution for a certain value of probability. qchisq(c(0.025), df=286, lower.tail=TRUE) For plotting the graph the command is: local({ + .x <- seq(213.788, 371.301, length.out=1000) + plotDistr(.x, dchisq(.x, df=286), cdf=FALSE, xlab=”x”, ylab=”Density”, + […]