Change in initial investment $\left(∆\mathrm{I}\right)=\mathit{₹}1200$ crores Marginal propensity to save (MPS) $=0.2$
(a) Investment multiplier (k) $=\frac{1}{\mathrm{MPS}}=\frac{1}{0.2}=5$
(b) Change in final income $\left(∆\mathit{Y}\right)=$ ?
$\mathrm{K}=\frac{∆\mathrm{Y}}{∆\mathrm{I}}$
$∆\mathrm{Y}=\mathrm{K}\times ∆\mathrm{I}$