Calculator User Manual

Chapter 13: Inferential Statistics and Distributions 332
Interpret the results.
The first line, (
159.74,173.94), shows that the 99 percent confidence interval for the
population mean is between about 159.74 centimeters and 173.94 centimeters. This is
about a 14.2 centimeters spread.
The .99 confidence level indicates that in a very large number of samples, we expect 99
percent of the intervals calculated to contain the population mean. The actual mean of
the population sampled is 165.1 centimeters, which is in the calculated interval.
The second line gives the mean height of the sample v used to compute this interval.
The third line gives the sample standard deviation
Sx. The bottom line gives the sample
size
n.
To obtain a more precise bound on the population mean m of women’s heights, increase
the sample size to 90. Use a sample mean v of 163.8 and sample standard deviation
Sx
6. Press † to move the cursor onto
Calculate, and
then press Í. The confidence interval is
calculated, and the
TInterval results are displayed
on the home screen.