Grouped standard deviation – HP 35s Scientific Calculator User Manual
Page 264
16-18
Thus, we would expect that only about 1 percent of the students would do better
than score 90.
Grouped Standard Deviation
The standard deviation of grouped data, S
xy
, is the standard deviation of data
points x
1
, x
2
, ... , x
n
, occurring at positive integer frequencies f
1
, f
2
, ... , f
n
.
Keys:
(In RPN mode)
Display:
Description:
S
Starts the initialization routine.
Stores 55 for the mean.
Stores 15.3 for the standard deviation.
D
value
Starts the distribution program and
prompts for X.
Enters 90 for X and calculates Q(X).
Keys:
(In RPN mode)
Display:
Description:
I
Starts the inverse routine.
Stores 0.1 (10 percent) in Q(X) and
calculates X.
Resumes the inverse routine.
Stores 0.8 (100 percent minus 20
percent) in Q(X) and calculates X.
∑
∑
∑
∑
−
−
=
1
2
2
)
f
(
f
)
f
x
(
f
x
S
i
i
i
i
i
i
xg