HP HP-67

Function Keys 113
2 @8 EED
29
€5
60
Y crs Jenter
35 7.00 Number of data pairs
(n) is now 7.
0 -21.57 Average low temperature.
h]
Average
high
temperature.
The illustration below represents what happens in the stack when you
press £ (). Press [ (&) and the contents of the stack registers are
changed...
...from this... ...to this.
T t _— t T
Z z —_— 2z z
Y y —>»Jost y Y
X X X X
!
x LASTX
Standard Deviation
The (§) (standard deviation) key is the key you use to calculate the
standard deviation (a measure of dispersion around the mean) of data
accumulated in secondary storage registers Rgy through Rg,.
When you press £ (3):
1. Sample x standard deviation (s,) is calculated using the data
accumulated in storage registers Rgs (2x?), Rgy (2x), and Rgg
(n) according to the formula:
The resultant value for standard deviation of x (sy) is seen in
the displayed X-register.