Inference aplet 11-15
Results The results are:
Confidence intervals
The confidence interval calculations that the HP 39gs can 
perform are based on the Normal Z-distribution or 
Student’s t-distribution. 
One-Sample Z-Interval
Menu name Z-INT: μ 1
This option uses the Normal Z-distribution to calculate a 
confidence interval for m, the true mean of a population, 
when the true population standard deviation, s, is known. 
Inputs The inputs are:
Result Description
Test T T-Test statistic.
Prob Probability associated with the T-Test 
statistic.
Critical T Boundary values of T associated with 
the α level that you supplied.
Field 
name
Definition
Sample mean.
σ Population standard deviation.
n Sample size.
C Confidence level.
x
HP 39gs English.book  Page 15  Wednesday, December 7, 2005  11:24 PM