Texas Instruments TI-83 PLUS User Manual

Page 387

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TI-83 Plus

Inferential Statistics and Distributions

384

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

þ

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

þ

of 163.8

and sample standard deviation

Sx

of 7.1 calculated from the larger

random sample. This time, use the

Stats

(summary statistics) input

option.

7. Press

|

8

to display the inferential stat

editor for

TInterval

.

Press

~

Í

to select

Inpt:Stats

. The editor

changes so that you can enter summary
statistics as input.

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