Answer: The value of x is 3.
Step-by-step explanation:
Since we have given that
10,11, 12 and x
Average of above numbers = 9
As we know that
Average is given by
[tex]\dfrac{\text{Sum of observation}}{\text{Number of observation}}\\\\\\\dfrac{10+11+12+x}{4}=9\\\\10+11+12+x=9\times 4\\\\33+x=36\\\\x=36-33\\\\x=3[/tex]
Hence, the value of x is 3.
