Question

the mean of 10 observations is 3.5.If two observations namely 3.5 and 2.5 are deleted,the new mean will be...

Answer 1

The answer is 5.125
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Answer 2

Let the observations be x₁,x₂,x₃,......,x₈,x₉,x₁₀ and let x₉=3.5,x₁₀=2.5
ATQ,
(x₁+x₂+x₃+.......+x₈+x₉+x₁₀)/10=3.5⇒x₁+x₂+x₃+.......+x₈+x₉+x₁₀=35
⇒x₁+x₂+x₃+.......+x₈+3.5+2.5=35⇒x₁+x₂+x₃+.......+x₈+6=35
⇒x₁+x₂+x₃+.......+x₈=35-6=29
If the two observations 2.5 and 3.5 are deleted,i.e.x₉ and x₁₀ are deleted,then the total number of observations=10-2=8
New mean=(x₁+x₂+x₃+.......+x₈)/8=29/8=3.625(Ans.)