Press the STAT key and ENTER to select EDIT. Now enter the homework data from lesson 2, question 17 (was penult or next to last). Your screen should appear as below.
Press the 2nd MODE (QUIT) or just go directly to STAT arrow over to CALC and ENTER to select 1-Var Stats. Now enter 2nd 1 (L1). Although this last aspect (L1) is optional, it can save a lot of grief, since you never know who set the defaults to what! Your screen should now appear as below.
![[x bar]](xbar.gif){kind=small}
is the arithmetic mean.
Also shown are the sum of the data elements and the sum of their squares.
Next is Sx. This is the sample standard deviation to be discuss in
lesson 5.
Next is ![[sigma sub x]](sigmax.gif)
.
This is the population standard deviation also to be discussed
later.
Last is n or the sample size.
Please note the arrow beside the n. If you arrow down, the 5-number summary will be displayed as below.
This is the topic of lesson 7, but note that the median (Med) is displayed there.
For large lists, sorting it first may facilitate finding the mode (or trimming it to find trimmed means). This can be accomplished by 2nd STAT (LIST), then arrow over to OPS ENTER (to select SortA(, then 2nd 1 L1)). The closing parenthesis is optional.
The midrange can be obtained by adding the 1 and 7 and dividing by 2. If you get 4.5, you forget to use parentheses! Using minX and maxX from the 5-number summary above may be helpful.
If your lists are missing, enter STAT, then 5 to run the SetUpEditor. Normally, lists L1-L6 are available. Additional lists may be named. These names are available under 2nd STAT or LIST. It also might be necessary to clear a list (arrow up to the list name and enter CLEAR. Elements may be inserted into or deleted from lists by use of the DEL or 2nd DEL = INS key. The author often rescales test scores (which were in L5) by the following command: ROUND(.9*L5,0)+11STO>L6. What does this do?
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