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Confidence Interval Command List
k
Z
Confidence Interval
1-Sample
Z
Interval
Menu: [Interval]-[One-Sample ZInt][Interval]-[One-Sample ZInt]One-Sample ZInt]-Sample ZInt]Sample ZInt] ZInt]ZInt]]
Description: This command obtains the confidence interval for the population mean when
the population standard deviation is known.
The confidence interval is obtained using the following expressions.
Left = o – Z
α
2
σ
n
Right = o + Z
α
2
σ
n
α
is the significance level, and 100 (1 –
α
)% is the confidence level. When the
confidence level is 95%, for example, you would input 0.95, which produces
α
= 1 – 0.95 = 0.05.
Definition of Terms
C-Level : confidence level (0
<
C-Level < 1)
σ
: population standard deviation (
σ
> 0)
List : list where sample data is located
Freq : frequency of sample (1 or list name)
o
: sample mean
n
: sample size (positive integer)
Calculation Result Output
Left : interval lower limit (left edge)
Right : interval upper limit (right edge)
o
: sample mean
x
σ
n
–1
: sample standard deviation (Displayed only for list format.)
n
: sample size
Example 1 (calculation with list)
list1 : { 299.4, 297.7, 301, 298.9, 300.2, 297 }
Population standard deviation : 3
Significance level : 5% ( = confidence level : 95%)
• Statistics Wizard Operation
(1) Input the data into [list1] in the Stat Editor.
(2) On the menu bar, tap [Calc] and then [Interval].
(3) Select [One-Sample ZInt] and [List], and then tap
[Next >>].
(4) Input values.
(5) Select List [list1] and Freq [1].
(6) Tap [Next >>].
7-10-2
Confidence Intervals
20070301