Every Normal model is defined by its parameters, the mean and the standard deviation. For each model described here, find the missing parameter. As always, start by drawing a picture.
a) μ = 20, 45% above 30; σ ?
b) μ = 88, 2% below 50; σ ?
c) σ = 5, 80% below 100; μ = ?
d) σ = 15.6, 10% above 17.2; μ = ?