Don <- read.table("https://husson.github.io/livre_exo/chap3_ex4.csv", header = TRUE, sep=";", encoding = "latin1", stringsAsFactors = TRUE)
by(Don[,"Distance"],Don[,"Sexe"],mean)
by(Don[,"Distance"],Don[,"Sexe"],sd)

## Question 2 et 3
by(Don[,"Distance"],Don[,"Sexe"],t.test,mu=12,conf.level=0.80)
by(Don[,"Distance"],Don[,"Sexe"],t.test,mu=12,conf.level=0.95)
by(Don[,"Distance"],Don[,"Sexe"],t.test,mu=12,conf.level=0.99)