problem-10.16

problem-10.16  If res stores the model, this can be done as follows:
> age.sort = sort(unique(age))
> pred.res = predict(res, newdata = data.frame(age = age.sort),int="conf")
> plot(mhr ~ age); abline(res)
> lines(age.sort,pred.res[,3], lty=2)
> lines(age.sort,pred.res[,2], lty=2)

The only change is the abbreviated int="cont".