A copper ball of mass $100\; gm$ is at a temperature T. It is dropped in a copper calorimeter of mass $100 \;gm$, filled with $170\; gm$ of water at room temperature. Subsequently, the temperature of the system is found to be $75^{\circ} C$. T is given by : (Given : room temperature = $30^{\circ}C$, specific heat of copper = $0.1 \;cal/gm^{\circ}C$)
