# Chapter 4 Discussion
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## Absence Interpretation
| Periods Absent | Probability of all day absence |
|:--------------:|:------------------------------:|
| a >= 6 | 1.0 |
| a >= 3 | 0.5 |
| a < 3 | 0.0 |
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## Speaker
| Input | Pattern output |
|:-----:|----------------|
| 1 | "welcome" |
| 2 | "students" |
| 3 | "_students_ welcome welcome _students_" |
| 4 | "_students_ welcome welcome _students_ students students _students_ welcome welcome _students_" |
| n | (previous output) (output before that) (output before that) (previous output) |
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## Trimult
Given a list of numbers, produce a list of all products of three terms in a row.
* `trimult [10,20,50] = [10000]`
* `trimult [1,2,3,4,5,6] = [6,24,60,120]`
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## Second and third
|Input|Output|
|-----|------|
| [1,5,10] | "The second and third items of [1,5,10] add to be 15" |
| [3,40,60,99] | "The second and third items of [3,40,60,99] add to be 100" |
Try two different ways!
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## Eighty-first
Find the eighty-first item in a list.
|Input|Output|
|-----|------|
| [0,2..200] | 162 |
|[110,120..]| 920 |
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