HP 50g Graphing Calculator - Manual (Page 599)

Page 18-32
Example 5 – Determine a 95% confidence interval for the mean of the
population if a sample of 50 elements has a mean of 15.5 and a standard
deviation of 5. The population’s standard deviation is unknown.
Press ‚Ù—@@@OK@@@ to access the confidence interval feature in the
calculator. Press — — @@@OK@@@ to select option 5. T-INT: μ. Enter the
following values:
When done, press @@@OK@@@. The results, as text and graph, are shown below:
The figure shows the Student’s t pdf for ν = 50 – 1 = 49 degrees of freedom.
Example 6 -- Determine the 99% confidence interval for the difference in means
of two populations given the sample data:
⎯x
1
= 157.8 , ⎯x
2
= 160.0, n
1
= 50,
n
2
= 55. The populations standard deviations are s
1
= 13.2, s
2
= 24.5.
Press ‚Ù—@@@OK@@@ to access the confidence interval feature in the
calculator. Press —@@@OK@@@ to select option 6. T-INT: μ1−μ2.. Enter the
following values:
hen done, press @@@OK@@@. The results, as text and graph, are shown below: