HP 50g User Manual download pdf (Page 163)

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4. Z-INT: p1− p2.: Confidence interval for the difference of two

proportions, p

-p

, 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

- µ

, 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 = 23.3, 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:

Press @GRAPH to see a graphical display of the confidence interval

information:

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HP 50g User Manual Page 163