A radioactive decay chain follows $N_1 \\to N_2 \\to N_3$ (stable), with decay constants $\\lambda_1 = 0.2$ hr$^{-1}$ and $\\lambda_2 = 0.1$ hr$^{-1}$. If a sample initially contains $N_1(0) = 1000$ atoms and $N_2(0) = 0$ atoms, what is the population of $N_2$ at time $t = 10$ hours?