$5\mathrm{.}6$ Try other starting values for the nlm program in Sect. $5\mathrm{.}7$ that fits a

standard deviation proportional to the mean. What range of values

provide reasonable answers with a relatively small number of iterations?

Does your finding depend on the size of the normal sample z$?$ What

happens if you start with invalid parameter values, such as negative

estimates of the standard deviation?