4. Z-INT: p
p .: Confidence interval for the difference of two
5. T-INT: 1 .: Single sample confidence interval for the population mean,
, for small samples with unknown population variance.
.: Confidence interval for the difference of the population
Example 1 – Determine the centered confidence interval for the mean of a
population if a sample of 60 elements indicate that the mean value of the
sample is x = 23.3, and its standard deviation is s = 5.2. Use
= 0.05. The confidence level is C = 1- = 0.95.
Select case 1 from the menu shown above by pressing @@@OK@@@ . Enter the
values required in the input form as shown:
Press @HELP to obtain a screen explaining the meaning of the confidence
interval in terms of random numbers generated by a calculator. To scroll
down the resulting screen use the down-arrow key ˜ . Press @@@OK@@@ when
done with the help screen. This will return you to the screen shown above.
To calculate the confidence interval, press @@@OK@@@ . The result shown in the
Press @GRAPH to see a graphical display of the confidence interval
, for large samples with unknown population
, for small samples with unknown population variances.