Bozzo
Check out DAP 2-2 which is a chart of climb rates/gradients/ground speeds. As a rule of thumb you can find a climb gradient (%) by dividing the rate of climb (ft/min) by the ground speed (knots).
If you apply the formula to your question 1200 ft/min divided by 200 kt gives 6%, and the DAP chart quotes a required ROC of 1155 ft/min for a 5.7% gradient at 200 kt.
Good luck.