Most probably, higher then yours.
If the boy's IQ is 122, then yes, 122 would be an IQ of an 11-year-old boy. It's an above average IQ with 100 being perfectly average.
His average IQ is 100, as is the average IQ of everyone
Well, the average IQ is 100, so 120 is classed as "above average". So it is very good, yes.
90-105 is the average IQ for anyone.
It means the boy has an average IQ.
The average IQ for anybody is 100.
By definition, an IQ of 100 is average.
The average IQ for any age is 100
It's fine. It's almost exactly average.
100. plus/minus 10 for the normal range (90-110).
The average IQ of the population is 100. IQ results don't depend on age or gender, so there is no difference in the average IQ for varying ages. Therefore, for a 15 year old boy, the average IQ is still 100.
No, that is not an average IQ. Anything between about from 90 to 110 is considered average.