A film-coating process produces films whose thicknesses are normally distributed with a mean of 110 microns and a
standard deviation of 10 microns. For a certain application, the minimum acceptable thickness is 90 microns.
a) What proportion of films will be too thin?
b) To what value should the mean be set so that only 1% of the films
will be too thin?
c) If the mean remains at 110, what must the standard deviation be
so that only 1% of the films will be too thin?