salt <- salt_study$Daily.Salt.Intake
strokes <- salt_study$Stroke.deaths.per.million
newsalt <- data.frame(salt=c(9.45, 10.85))
bestline=lm(strokes~salt)
predict(bestline, newsalt, interval = "predict")

plot(main="Salt Study", xlab="Daily Salt Intake (g/day)", ylab="Stroke deaths per million people", salt, strokes, xlim=c(7.0, 12.0),ylim=c(0, 4000))
bestline=lm(strokes~salt)
abline(bestline)
summary(bestline)
cor(salt, strokes)