HP 48gII - Manual (Page 599)

Page 18-28
3. Z-INT: 1 p.: Single sample confidence interval for the proportion, p, for
large samples with unknown population variance.
4. Z-INT: p 1− p2.: Confidence interval for the difference of two proportions,
p
1
-p
2
, for large samples with unknown population variances.
5. T-INT: 1 µ.: Single sample confidence interval for the population mean,
µ, for small samples with unknown population variance.
6. T-INT: µ1−µ2.: Confidence interval for the difference of the population
means, µ
1
- µ
2
, for small samples with unknown population variances.
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 = 23.2, and its standard deviation is s = 5.2. Use α = 0.05.
The confidence level is C = 1- α = 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
calculator is: