12/15×6/7 = 24/35 9/8×4/12 = 3/8 13/15×6/7 = 26/35
I believe your interval is [-2,2]: all numbers between -2 and +2.
Then the ave. r. of c. on this interval is:
f(2) - f(-2) 4^2 + 2 - {4^(-2) + 2}
------------- = ------------------------------
2 - (-2) 4
16 - (1/16) 15 15/16
= --------------------- = --------------- = 3.98 or 255/64
4 4
