65
Copyright © Lexibook 007
ENGLISH
Average and sample standard deviation for Benjamin’s marks as well as
those of his friends?
[MODE] 2
-> SD is displayed
[SHIFT][CLR] 1 [=]
-> clear
8 [DT]
-> n= | 1 beginning of data entry
9 [.] 5 [DT]
-> n= | 2
10 [DT] [DT]
-> n= | 4
or 10 [SHIFT] [;] 2 [DT] to enter same amount twice.
And so on and so forth:
10 [.]5 [DT]
11 [DT]
13 [DT]
13[.]5 [DT]
14 [.]5 [DT]
15 [DT]
We display n and check that the number displayed corresponds to the
number of values inputted:
[SHIFT][S-SUM] 3 [=] -> n | 10.
[SHIFT] [S-VAR] 1 [=] -> x | 11.5
Their average is 11,5.
[SHIFT] [S-VAR] 3 [=] -> x n-1 | 2.34520788 thus the standard deviation.
If we wish to calculate the variance, we press
[x
][=] -> Ans2 | 5.5 is the variance.
We take up the same experience with the maths exam in which the students
obtained the following notes:
[SHIFT][CLR] 1 [=]
-> clear
To check:
[SHIFT][S-SUM] 3 [=] -> n | 0.
Beginning of data entry :
4 [DT]
-> n= | 1.
…
And so on, up to 18 [DT]
[SHIFT][S-SUM] 3 [=] -> n | 10.
[SHIFT] [S-VAR] 1 [=] -> x | 11.5
Their average is also 11,5.
[SHIFT] [S-VAR] 3 [=] -> x n-1 | 5.088112507 thus the standard deviation.
student A
B
C
D
E
F
G
H
I
J
marks
4
7.5 12
8
8
8
14.5 18
17
18
SC460IM0237.indb 65
20/6/07 15:28:10
