problem-1.9

problem-1.9  Using range() makes these straightforward.
> mini = c(15.9, 21.4, 19.9, 21.9, 20.0, 16.5, 17.9, 17.5)
> range(mini)
[1] 15.9 21.9
> mean(mini)
[1] 18.88
> range(mini - mean(mini))
[1] -2.975  3.025