Homework Problem 25, Due Monday May 3.
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Access the data "geyser" included as part of standard Splus. It is 
a list with two components, "waiting" (which should be 299 times 
in minutes between successive eruptions of the Old Faithful geyser 
in Yellowstone park) and "duration" (the eruption times, also in
minutes).

(i) Create a scaled relative-frequency histogram for the 
geyser$waiting  dataset. Over-plot two kernel density estimators, 
with your choice of probability density as kernel: one with 
bandwidth = 0.5, and one with bandwidth b=3.

(ii) Fit a mixture of log-normal densities, with 2 or 3 components,
to the dataset, and compare (visually) the quality of fit with the 
density estimates you calculated in (i).