Efficiency Of Boiler!

If-----
Duration of trial of boiler is 16 hrs.
Total heating surface is 3000 m[sup]2[/sup].
Total grate area is 4 m[sup]2[/sup].
Mean absolute pressure is 12.5 bar.
Total coal burned is 6850 kg.
Total mass of water evaporated is 65000 kg.
Temperature of feed water is 40[sup]o[/sup] C.
Conditions of steam is 0.93 dry.

then determine ---

Mas of coal burned per m square of grate area per hour.
Mass of water evaporated per kg of coal under actual condition.
Equivalent evaporation per kg of coal.
Equivalent evaporation per m square of total heating surface per hour.
Efficiency of boiler.

(the calorific value of coal is 27720 KJ/kg.)