Question

The mean of 11 result is 30.if the mean of first 6 is 28 and that of last 6 is 32 find the 6th result

Answer 1

let 6th be x
let sum of first 5 be S₁ and last 5 be S₂
then (S₁+x)/6=28..............................S₁=28*6-x
(x+S₂)/6=32......................................S₂=32*6-x
(S₁+x+S₂)/11=30...............................S₁+S₂=30*11-x
solving all 3
28*6-x+32*6-x=30*11-x.....................x=28*6+32*6-30*11=30