HP HP-67 - Mean

Function Keys 111
4 Sum of x values from
register Ry.
5
Sum
of
squares
of
x
values from register Rs.
6 Sum of y values from
register Rg.
7 Sum of squares of y
values from register R;.
8 Sum of products of x and
y values from register Rg.
9 Number of entries (n = 3).
By using the function in conjunction with the key, you can
actually maintain two complete sets of products and sums in your
HP-67.
Mean
The (mean) key is the key you use to calculate the mean (arithmetic
average) of data accumulated in secondary registers Rgs, Rge, and
RSQ .
When you press [ (3):
1. The mean (X)of x is calculated using the data accumulated in
register Rg, (2x) and Rg, (n) according to the formula:
n
i=——1—2 X4 (Thatis, EM =5(>
S9
The resultant value for X is seen in the displayed X-register.
. The mean (y) of y is calculated using the data accumulated in
register Rgg (Zy) and register Rgg (n) according to the formula:
n
T=—> v (Thar is, 8 =y)
n = S9
The resultant value for y is available in the Y-register of the
stack .