# Problem 18.7
errorspc=read.table("errorspc.txt",header=T)
p=errorspc[,1]/errorspc[,2]
plot(p)
pbar=mean(p)
abline(h=pbar,lty=3)
lcl=pbar-3*sqrt(pbar*(1-pbar)/200)
ucl=pbar+3*sqrt(pbar*(1-pbar)/200)
c(lcl,ucl)
abline(h=ucl,lty=2)

# Problem 18.8
telespc=read.table("telespc.txt")
p=telespc[,2]/telespc[,1]
plot(p)
pbar=mean(p)
abline(h=pbar,lty=3)
nbar=mean(telespc[,1])
lcl=pbar-3*sqrt(pbar*(1-pbar)/nbar)
ucl=pbar+3*sqrt(pbar*(1-pbar)/nbar)
c(lcl,ucl)
abline(h=lcl,lty=2)
abline(h=ucl,lty=2)
range(p)
plot(p,ylim=c(.07,.16))
abline(h=pbar,lty=3)
abline(h=lcl,lty=2)
abline(h=ucl,lty=2)

# Problem 18.14
teller=scan("teller.txt")
plot(teller)
cbar=mean(teller)
abline(h=cbar,lty=3)
lcl=cbar-3*sqrt(cbar)
ucl=cbar+3*sqrt(cbar)
c(lcl,ucl)
abline(h=ucl,lty=2)
plot(teller,ylim=c(0,13))
abline(h=cbar,lty=3)
abline(h=ucl,lty=2)