Maintenance script: Initial automated import

2016-02-24T18:16:14Z

Initial automated import

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{{Template:TI-BASIC:Command
|picture=MEAN.GIF
|summary=Finds the mean (the average) of a list.
|syntax=mean(''list'',[''freqlist''])
|location=Press:
# 2ND LIST to enter the LIST menu.
# LEFT to enter the MATH submenu.
# 3 to select mean(, or use arrows.
|compatibility=TI-83/84/+/SE
|size=1 byte
}}

The mean( command finds the [http://en.wikipedia.org/wiki/Mean mean], or the average, of a list. It's pretty elementary. It takes a list of real numbers as a parameter. For example:

:Prompt L1
:Disp "MEAN OF L1",mean(L1

That's not all, however. Awesome as the mean( command is, it can also take a frequency list argument, for situations when your elements occur more than once. For example:

:Disp mean({1,2,3},{5,4,4})

is short for

:mean({1,1,1,1,1,2,2,2,2,3,3,3,3})

The frequency list {5,4,4} means that the first element, 1, occurs 5 times, the second element, 2, occurs 4 times, and the third element, 3, occurs 4 times.

= Advanced Uses =

You can also use the frequency list version of mean( to calculate weighted averages. For example, suppose you're trying to average grades in a class where homework is worth 50%, quizzes 20%, and tests 30%. You have a 90% average on homework, 75% on quizzes (didn't study too well), but 95% average on tests. You can now calculate your grade with the mean( command:

:mean({90,75,95},{50,20,30

You should get a 88.5 if you did everything right.

Frequency lists don't need to be whole numbers. Amazing as that may sound, your calculator can handle being told that one element of the list occurs 1/3 of a time, and another occurs 22.7 times. It can even handle a frequency of 0 - it will just ignore that element, as though it weren't there. In particular, mean(L1,L2) is effectively equivalent to sum (L1*L2)/sum(L2).

One caveat, though - if all of the elements occur 0 times, there's nothing to take an average of and your calculator will throw an error.

= Error Conditions =

* '''[[TI-BASIC:Errors#datatype|ERR:DATA TYPE]]''' is thrown, among other cases, if the data list is complex, or if the frequencies are not all positive and real.
* '''[[TI-BASIC:Errors#dimmismatch|ERR:DIM MISMATCH]]''' is thrown if the frequency list and the data list have a different number of elements.
* '''[[TI-BASIC:Errors#divideby0|ERR:DIVIDE BY 0]]''' is thrown if the frequency list's elements are all 0.

= Related Commands =

* [[TI-BASIC:Median|median(]]
* [[TI-BASIC:Stddev|stdDev(]]
* [[TI-BASIC:Variance|variance(]][[Category:TI-BASIC]]
[[Category:TIBD]]

TI-BASIC:Mean - Revision history

Maintenance script: Initial automated import