Q. 154.2( 6 Votes )

The mean of six numbers is 23. If one of the numbers is excluded, the mean of the remaining numbers is 20. Find the excluded number.

Answer :

Let suppose the numbers are = n1, n2, n3, n4, n5, n6



Given mean = 23


So,



n1 + n2 + n3 + n4 + n5 + n6 = 23×6 = 136 ……….(i)


Let suppose excluded number be n4


N = 5


Mean of remaining numbers = (given)


n1 + n2 + n3 + n5 + n6 = 20 × 5 = 100 ……….(ii)


Subtract the (ii) equation from (i) equation


We get;


n4 = 138 – 100 = 38


So, the excluded number is 38.


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