b$)$ A $910$ mm shaping machine $($maximum quick return ratio $=3$:$2)$ is used to remove $6$ mm thickness from the top of a mild steel plate: $450$ mm x $300$ mm$.$ The tool material is HSS$.$ Feed is $0\mathrm{.}3$ mm per stroke. Estimate the machining time, assuming reasonable data. b$)$ A $910$ mm shaping machine $($maximum quick return ratio $\backslash (=3$: $2\backslash ))$ is used to remove $6$ mm thickness from the top of a mild steel plate: $\backslash (450\backslash$mathrm$\{$~mm$\}\backslash$times $300\backslash$mathrm$\{$~mm$\}\backslash ).$ The tool material is HSS$.$ Feed is $0\mathrm{.}3$ mm per stroke. Estimate the machining time, assuming reasonable data.