HP 50g User Manual page 597

Example 2 -- Data from two samples (samples 1 and 2) indicate that x =
1
57.8 and x = 60.0. The sample sizes are n = 45 and n = 75. If it is
2 1 2
known that the populations' standard deviations are = 3.2, and = 4.5,
1 2
determine the 90% confidence interval for the difference of the population
means, i.e., - .
1 2
Press ‚Ù—@@@OK@@@to access the confidence interval feature in the
calculator. Press ˜@@@OK@@@ to select option 2. Z-INT:
1 – 2.. Enter the
following values:
When done, press @@@OK@@@. The results, as text and graph, are shown below:
The variable represents 1 – 2.
Example 3 – A survey of public opinion indicates that in a sample of 150
people 60 favor increasing property taxes to finance some public projects.
Determine the 99% confidence interval for the population proportion that would
favor increasing taxes.
Press ‚Ù—@@@OK@@@to access the confidence interval feature in the
calculator. Press ˜˜ @@@OK@@@ to select option 3. Z-INT:
1 – 2.. Enter the
following values:
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