"A packet of mince contains 500g of mince. Suppose the actual weight (x) of
these packets is normally distributed with a mean of 512 grams and a standard
deviation of 8 grams. What is the probability of picking a packet between 504
and 520g?"
Firstly open the main window and add the list editor from the toolbar.
Opening the list editor should make the Calc menu appear in the menubar at the top of the window.
Select Calc->Distribution. This will make a popup appear with some options
The Type dropdown needs to say Distribution.
The second dropdown should say Normal CD. After that is selected tap Next. A new dialog box will appear.

For our problem the lower bound is 504, the upper bound is 520, the standard deviation is 8 and the mean is 512. Tap Next when this has been entered. The answer will appear with a probability of 0.683
Tap the graph icon in the toolbar to view the distribution.

Viola!
Here is a link to other CAS calculator posts.