A boiler produces \(1000 \mathrm{~kg}\) of steam \(/ \mathrm{h}\) at a pressure of \(10 \mathrm{bar}\) abs. and \(0.95 \mathrm{dry}\) from water at \(40^{\circ} \mathrm{C}\). It is ascertained that \(10 \%\) of coal is unburnt at grate. If the efficiency of boiler alone is \(75 \%\), find the efficiency of the boiler and grate combined. C.V. of coal is \(30980 \mathrm{~kJ} / \mathrm{kg}\). Assume specific heat of water as \(4.1868 \mathrm{~kJ} / \mathrm{kg} . \mathrm{K}\).