My estimate is that you will get ((280(89/99)^1.1)+(280(280(83/99)^1.1))/2 = 239.84 x 10.000 = ~2.4 million Ranged exp with 10K chins. For every Ranged experience you will need to do 2.5 damage. These 2.4 million Ranged exp's means you will have done 2.400.000 x 2.5 = 6 Million damage.
6 million damage will gain you 6.000.000 x 0.133 = ~800K Constitution exp.
Your welcome.