Competitive-advantage period

A company earns $\text{NOPAT}_1 = N$ on existing capital in perpetuity. In each year $t = 1, \dots, T$ it invests $I_t = (g/R)\text{NOPAT}_t$, and each such investment earns $R$ in perpetuity from year $t+1$. After year $T$, new investments earn exactly $W$. (a) Prove that

(b) Show that as $T \to \infty$ (with $g < W$) this tends to the value-driver formula (6.13). (c) Evaluate for $N$ = ₹500 cr, $g$ = 8%, $R$ = 30%, $W$ = 12% and $T$ = 5, 10, 20. What fraction of the infinite-horizon value of growth does a 10-year advantage capture?