The arithmetic mean of the square
of 5 distinct quantities is 45.
Later it was found that one quantity
yous wrongly taken as 5 instead of 7.
Find the corrected arithmetic mean.
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Answer:
Mean of 9 observation =45.
x
ˉ
=45
n=9
x
ˉ
=
n
∑x
∑x=
x
ˉ
n=45×9=405
Sum of all observation are 405.
Now an observation was wrongly taken as 42 for 24.
∴ 42−24=18 was mistakely added more.
∴ ∑x−18=387=∑y [the correct sum of all observation.]
∴
y
ˉ
=
n
∑y
=
9
387
=43
∴43 is the correct mean.
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