Math, asked by Shivu3375, 1 year ago

The mean of 8 numbers is 42. If 1 number is excluded from their mean it becomes 39.what will be the excluded number?

Answers

Answered by Bulokamma
14
Number is63
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Answered by GeniusYH
26
8 numbers say 'a,b,c,d,e,f,g,h'
their
1st case :
mean = (a+b+c+d+e+f+g+h)/8 = 42

Transpose 8 to RHS.
then it becomes
a+b+c+d+e+f+g = 42*8 = 336 - [eq1]

2nd case :
(a+b+c+d+e+f+g)/7 =39
(because h is excluded)

Transpose 7 to RHS.
then it becomes
a+b+c+d+e+f+g = 39*7 = 273 - [eq2]

Solve [eq1 and 2], we get:
Subtract [eq2 from 1];
a,b,c,d,e,f,g will be cancelled as in the above picture...

h then comes = 63
Therefore the excluded number is 63.
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GeniusYH: this is very detailed answer
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