The assembly consists of two red brass $C 83400$ copper rods $A B$ and $C D$ having a diameter of $30 \mathrm{mm},$ a 304 stainless steel rod $E F$ having a diameter of $40 \mathrm{mm}$ and a rigid member $G .$ If the supports at $A, C$ and $F$ each have a stiffness of $k=200 \mathrm{MN} / \mathrm{m}$, determine the average normal stress developed in the rods when the load is applied.