Average of A, B and C is given by:

Considering option,

In 1st we get product of a and b which is not required In 2nd we get fraction 1.5 which doesnt help in finding average In 3rd we get (a+b)/4 after 2 operations which doesn't give average in further operations. only in 4th option we get overall and exact average of A , B and C .

/(X(@ (/(@(B, A), 2), C), 3), 2) = /(X(@ (/(A+B)/2), 2), C), 3), 2)

= /(X(@ (A+B), C), 3), 2) = /(X((A+B, C)/2, 3), 2)

= /[(A+B+C)/6,2]

= (A+B+C)/3