Given X1=20 and X2= -20. The arithmetic mean will be:
-infinity
-impossible
-difficult to tell
-zero
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Answer:
Mean is the sum of the data values divided by the total number of data values.
Given that mean of 20 observations x
1
,x
2
,...,x
20
is m
⟹m=
20
x
1
+x
2
+x
3
+...+x
20
------(1)
New mean after increasing first ten numbers by 8 and decreasing next ten numbers by 8 is n
⟹n=
20
x
1
+8+x
2
+8+....+x
10
+8+x
11
−8+...+x
20
−8
⟹n=
20
x
1
+x
2
+x
3
+...+x
20
------(2)
subtracting (1) and (2) we get
m−n=
20
x
1
+x
2
+...+x
20
−
20
x
1
+x
2
+...+x
20
⟹m−n=0
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