A boy of height 165 cms is replaced by another which deceases the average height of the group of 34 boys by 1 cms the height of the new boy is
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Answer :-
let x = sum of heights of the other original set of'
students, except for the replaced student
let y = the height of the new student
original average
(x + 165 ) / 34 = mean
new average
(x + y ) / 34 = mean - 1
original average
(x + 165 ) = mean * 34
new average
(x + y ) = mean * 34 - 34
original average
x = mean * 34 - 165
new average
(x + y ) = mean * 34 - 34
from the new average we have
(mean * 34 - 165 + y ) = mean * 34 - 34
-165 + y = -34
y = 165 - 34 = 131 cm
the height of the new student is 1
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