$1-$ Steady$-$state temperatures $(K)$ at three nodal points of a long rectangular rod are as shown. The rod experiences a uniform volumetric generation rate of $5{10}^7\frac{W}{m^3}$ and has a thermal conductivity of $20\frac{W}{m}*K.$ Two of its sides are maintained at a constant temperature of $300$ K $,$ while the others are insulated. Determine the temperatures at nodes $1,2,$ and $3.(25\%)$