R code for example 8.11

## input observations

obs <- c(4.68, 4.13, 4.8, 4.63, 5.08, 5.79, 6.29, 6.79, 4.93, 4.25, 5.7, 4.74, 
    5.88, 6.77, 6.04, 4.95)


xbar <- mean(obs)
xbar

## [1] 5.341

s <- sd(obs)
s

## [1] 0.8483

tscore <- qt(1 - 0.025, 15)
tscore

## [1] 2.131

upperbound <- 5.34 + 2.131 * 0.8483/sqrt(16)
upperbound

## [1] 5.792

lowerbound <- 5.34 - 2.131 * 0.8483/sqrt(16)
lowerbound

## [1] 4.888