Read this: State schools in Somerset are provided by three local education authorities: Bath and North East Somerset, North Somerset, and the larger Somerset County Council. All state schools are comprehensive. In some areas primary, infant and junior schools cater for ages four to eleven, after which the pupils move on to secondary schools. There is a three-tier system of first, middle and upper schools in the Cheddar Valley, and in West Somerset, while most other schools in the county use the two-tier system. Somerset has 30 state and 17 independent secondary schools; Bath and North East Somerset has 13 state and 5 independent secondary schools; and North Somerset has 10 state and 2 independent secondary schools, excluding sixth form colleges.

What is the average class size in Somerset independent secondary schools?
What is the answer? (If it cannot be answered, return "unanswerable")
unanswerable