# A7
data <- data.frame( aj=41:51, 
                    hj=c(1,9,13,13,20,15,10,7,5,4,3) )

# b
data$fj <- data$hj/sum(data$hj)
data$Hj <- cumsum(data$hj)
data$Fj <- data$Hj/sum(data$hj)

# c
plot(data[c("aj","hj")],type="h")

# d
rawData <- rep(data$aj,times=data$hj)
Fn <- ecdf(rawData)
plot(Fn)

# e
Fn(44)

# f
Fn(50) - Fn(44)