Question

The mean of 3 numbers is 12 two of the numbers are 9 and 14 what is the third number

Answer 1

let 3 numbers be x1,X2,X3
let two numbers x1=9 and X2=14

x1+X2+X3/3 =12

9+14+X3/3=12

23+X3=36

X3=36-23=13