http://wiki.stat.ucla.edu/socr/index.php/SOCR_EduMaterials_Activities_Binomial_Distributions # Exercise 1: # To graph a binomial distribution in R # First we can calculate all probabilities # X is binomial(10,0.5) x <- seq(0,10) px <- dbinom(x, size = 10, prob = 0.5) barplot(px, space = 0, xlab = "X", ylab = "P(X)", ylim = c(0, .25), main = "Binomial probability distribution", names.arg =x) #a. X is b(10,0.5) , find P(X = 3), E(X), sd(X) dbinom(3, 10, 0.5) ex <- sum(x*px) sdx <- sqrt(sum(x ^ 2 * px) - ex ^ 2) #b. X is b(10,0.1) , find P(1 <= X <= 3) sum(dbinom(1:3, 10, 0.1)) #or pbinom(3, 10, 0.1) - pbinom(0, 10, 0.1) #c. X is b(10,0.9) , find P(5 < X < 8), P(X < 8), P(X <= 7), P(X >= 9) pbinom(7, 10, 0.9) - pbinom(5, 10, 0.9) pbinom(7, 10, 0.9) pbinom(7, 10, 0.9) pbinom(8, 10, 0.9, lower.tail = FALSE) #d. X is b(30,0.1) , find P(X > 2) pbinom(1, 30, 0.1, lower.tail = FALSE) #or 1 - pbinom(1, 30, 0.1) #Exercise 5: par1 <- par() par(bg = "KHAKI") x <- seq(0, 10) px <- dhyper(x, 13, 39, 10) barplot(px, space = 0, xlab = "X", ylab = "P(X)", ylim = c(0, .35), main = "Hypergeometric probability distribution", col.main = "blue", names.arg =x, cex.names = .8, las = 2, col = "skyblue") #Exercise 6: P(X = 5) dhyper(5, 13, 39, 10) #Exercise 7 and 8: x <- seq(0, 10) px <- dhyper(x, 50, 950, 10) barplot(px, space = 0, xlab = "X", ylab = "P(X)", main = "Hypergeometric probability distribution", col.main = "blue", names.arg =x, cex.names = .8, las = 2) dhyper(2, 50, 950, 10) dbinom(2, 10, 0.05) #Exercise 9 x <- seq(0, 20) px <- dhyper(x, 40, 10, 20) barplot(px, space = 0, xlab = "X", ylab = "P(X)", ylim = c(0, .3), main = "Hypergeometric probability distribution \n and Binomial approximation", col.main = "blue", names.arg =x, cex.names = .8, las = 2, col = "skyblue") py <- dbinom(x, 20, 0.8) barplot(py, space = 0, xlab = "X", ylab = "P(X)", add = TRUE, col = "transparent", yaxt = "n", border = "red") ================================================================================== http://wiki.stat.ucla.edu/socr/index.php/SOCR_EduMaterials_Activities_More_Examples #Example 2 #a. phyper(0, 10, 990, 50, lower.tail = FALSE) phyper(0, 5, 495, 25, lower.tail = FALSE) #b. phyper(1, 10, 990, 50, lower.tail = FALSE) phyper(1, 5, 495, 25, lower.tail = FALSE) #c. phyper(1, 100, 900, 50, lower.tail = FALSE) phyper(1, 50, 450, 25, lower.tail = FALSE) #Example 3: pbinom(309, 567, .58, lower.tail = FALSE)