HP 35s

16-18 Statistics Programs
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
)fx(
fx
S
i
i
ii
ii
xg