ATPL Moving Mass problem
"An aircraft has a loaded mass of 5500 lb. The CG is 22 in. aft of the datum. A passanger, mass 150lb, moves aft from row 1 to row 3 a distance of 70 in. What will be the new position of the CG.(All dim. aft of the datum)"
Heres how i failed, i took 5500lb*X / 70in =150 lb, X= 2.1
So i expected to get new CG at 2.1in+22in = 24.1
Book says it should be 23.9.
What have i done wrong? Any ideas?