# Vector Summations - HP 25 Owner's Handbook Manual

Programmable scientific calculator.

70
Funclon K-
The correct values for mean and stand
ard
deviation are
now
obtainable by pressing
[Xl
and
~
.
For example, suppose the 62-year old member of the
sample
as given above were to lose his position as one of the wealthiest
persons because of a series of ill-advised investments in
cocoa
futures. To account for the change in data if he were
replace
d
in the sample by a 21-year old rock musician
:
Press
62
D
~
21
Ell
Display
62.
9.00
21.
10.00
Data to be replaced
.
Number of entries
(n)
is now nine.
The new
data.
Number of entries
(n)
is ten
aga
in
.
The new data has been calculated into each of the summations
present in the storage registers. To
see
the new mean and
standard deviation
:
Press
D@
DO
Display
60.30
17.09
The new average (mean)
age
.
The new standard deviation
.
Vector Summations
The
Ell
key can be used to sum any quantities that are in the
x-
and Y -registers
.
You can even perform vector addition and
subtraction using rectangular to polar coordinate conversion
and the
Ell
and
~
keys
.
Example: In his converted Swordfish aircraft, grizzled bush
pilot Apeneck Sweeney reads an air speed of 150 knots and
a
0
from his instruments
.
The Swordfish
is
also
being buffeted by a headwind of 40 knots from
a
bearing of
025°
.
What is the
a
ctual ground speed and course of the Sword-
fish?
Method: The course and ground speed are equal to the sum
of the instrument vector and the wind vector. The
vectors
are converted to rectangular coordinates and summed using
the
Ell
and
[[]
keys
.
Their sum is recalled by recalling the
values
in storage registers
R4
O:y) and R7 (Ix), and the new
rectan-
gular coordinates are then converted back to polar
coordinates