Comparison of Frequency Distributions for 2 populations (unpaired data)

[hubie]

1. Can I get a jpg / png instead of pdf?

Easy. To see what types you can do, check out the help:

?png

It will show you how you can do bmp, jpg, png, and tiff.

2. Will it plot a normal distribution on top of each frequency-density plot using the calculated mean/sd?

Check out this paper on fitting distributions. In particular, look at page 16 (the code for that plot is on page 15).

3. How can I control the width of the histogram bars (I would like them at 10, as my original - R seems to have used 20)?

Check out the help for the histogram function:

?hist

I believe the parameter you are interested in is "breaks," and some examples are given. Another helpful page is here.