# R-program for Supplementary Exercise 6.140 of IPS7e
# see R-program for 6.13 for more details about the commands

dms <- read.csv("r:/Chapter 6/ex06_140.csv")

# (a)
stem(dms$odor)
qqnorm(dms$odor)
qqline(dms$odor)

# (b)

# write a function to do the calculation
z.ci = function(a, sd, conf.level=0.95){
   lower = mean(a) - qnorm(1-(1-conf.level)/2)*sd/sqrt(length(a))
   upper = mean(a) + qnorm(1-(1-conf.level)/2)*sd/sqrt(length(a))
   return(as.vector(c(lower,upper)))
}
z.ci(dms$odor, sd=7, conf.level=0.95)

# use add-on library TeachingDemos
library(TeachingDemos)
z.test(dms$odor, sd=7, conf.level=0.95)

# (c)

# write a function to do the calculation
z.mytest = function(a, mu, sd){
   zeta = (mean(a)-mu)/(sd/sqrt(length(a)))
   return(zeta)
}
z <- z.mytest(dms$odor, mu=25, sd=7); z
p <- 1-pnorm(z); p

# use add-on library TeachingDemos
library(TeachingDemos)
z.test(dms$odor, mu=25, alternative="greater", sd=7, conf.level=0.95)