Casio fx-9750GII User Manual

6-35
6. Confidence Interval
Important!
• Confidence interval calculations cannot be performed on the fx-7400GII.
A confidence interval is a range (interval) that includes a statistical value, usually the
population mean.
A confidence interval that is too broad makes it difficult to get an idea of where the population
value (true value) is located. A narrow confidence interval, on the other hand, limits the
population value and makes it difficult to obtain reliable results. The most commonly used
confidence levels are 95% and 99%. Raising the confidence level broadens the confidence
interval, while lowering the confidence level narrows the confidence level, but it also
increases the chance of accidently overlooking the population value. With a 95% confidence
interval, for example, the population value is not included within the resulting intervals 5% of
the time.
When you plan to conduct a survey and then
t test and Z test the data, you must also consider
the sample size, confidence interval width, and confidence level. The confidence level changes
in accordance with the application.
1-Sample
Z Interval calculates the confidence interval for an unknown population mean when
the population standard deviation is known.
2-Sample
Z Interval calculates the confidence interval for the difference between two
population means when the population standard deviations of two samples are known.
1-Prop
Z Interval calculates the confidence interval for an unknown proportion of successes.
2-Prop
Z Interval calculates the confidence interval for the difference between the proportion
of successes in two populations.
1-Sample
t Interval calculates the confidence interval for an unknown population mean when
the population standard deviation is unknown.
2-Sample
t Interval calculates the confidence interval for the difference between two
population means when both population standard deviations are unknown.
On the initial STAT mode screen, press (INTR) to display the confidence interval menu,
which contains the following items.
• (INTR)(Z) ...
Z intervals (page 6-36)
(t) ...
t intervals (page 6-37)
After setting all the parameters, use A to move the highlighting to “Execute” and then press
the function key shown below to perform the calculation.
• (CALC) ... Performs the calculation.
• There is no graphing for confidence interval functions.
S General Confidence Interval Precaution
Inputting a value in the range of 0  C-Level<1fortheC-Level setting sets a value you input.
Inputting a value in the range of 1  C-Level < 100 sets a value equivalent to your input divided
by 100.

Casio fx-9750GII Specifications

General

Type	Graphing
Cover	-
Form factor	Desktop
Control type	Buttons
Product color	Blue
Digits	- digits
Display tilting	No
Display resolution	64 x 128 pixels
Display number of lines	8 lines
Display number of characters	21
Battery type	AAA
Power source	Battery
Auto power off	Yes
Number of batteries supported	4
Flash memory	0.061 MB
Storage media type	Flash
Symbolic notation	Square root
Conversion between	Decimal, Percent

Weight and Dimensions

Depth	180.5 mm
Width	87.5 mm
Height	21.3 mm
Weight	205 g