Question

The mean of 100 observations is 50 .if one of the observation which was 50 is replaced by 150 the resulting mean will be ------------

Answer 1

Hi ,

We know that,
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Mean

=( sum of the observations )/( number

of observations )
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According to the given problem ,

i )Sum of the 100 observations/ 100

= mean

Sum of the 100 observations

= 50× 100

= 5000 ------( 1 )

ii ) if one of the observation 50

replaced by 150

New Sum of the 100 observations

= 5000 - 50 + 150 [ from ( 1 ) ]

= 5100 ---( 2 )

New mean = ( 2 )/ 100

= 5100/ 100

= 51

I hope this helps you.

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Answer 2

As we know formula for mean is →

Sum of observations/ Number of observations

So, if mean of 100 observations is 50 , then sum of hundred observations = No of observations× Mean
= 100×50
=5000

Now as we have told , An observation 50 was replaced by 150 . So new sum of observations→

5000-50+150
= 5000+100
= 5100

New mean → 5100/100

= 51.

Answer → New mean is 51.
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