Known
Find
the 99% confidence interval for the mean when =
6 using the following data:
| 27 | 16 | 9 | 14 | 32 | 15 | 16 | 18 | 16 | 13 |
by pressing STAT and selecting 1:Edit by pressing ENTER.
The result is shown below
Next
press STAT, then RIGHT ARROW twice to TESTS. Press 7
to select 7:ZInterval. Data is already highlighted (if not already highlighted,
LEFT ARROW to highlight it), so press ENTER to select the data mode.
Make sure the defaults of
for List: and 1 for Freq: are also listed.
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ARROW DOWN once
and enter 6 next to :.
ARROW DOWN 3 times to C-LEVEL:. Enter the confidence interval as
a decimal fraction: .99 Then ARROW
DOWN once to Calculate
and then press ENTER. The results are shown below.
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The final screen reports
not only the confidence interval of the mean 
of (12.713, 22.487) in interval
notation, but also the mean and standard deviation of the sample data. The confidence
interval of the mean,,
of
(12.713, 22.487) can also be
written as 12.713 < < 22.487.
Find
the 90% confidence interval of the mean when 
=
182, =
8, and n = 50.
Press STAT, then RIGHT ARROW twice to TESTS. Press 7 to select 7:ZInterval. Data is highlighted.
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ARROW RIGHT once
to Stats and press ENTER. Stats is now highlighted. ARROW DOWN
once and enter the value of 8 for .
ARROW DOWN once and enter 182 for ,
then ARROW DOWN once again, and enter 50 for n.
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ARROW DOWN once to C-Level and enter 90% as the decimal .9. ARROW DOWN one last time to Calculate and then press ENTER. The results are shown below.
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The resulting
confidence interval of the mean,,
in interval notation is (180.14, 183.86),
or 180.14 <
< 183.86
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