Problem $8.$ Cold Working and Mechanical Properties

We want a $\backslash (\backslash$mathrm$\{$Cu$\}-30\backslash \%\backslash$mathrm$\{$Zn$\}\backslash )$ brass plate originally $1\mathrm{.}2$ in $.$ thick to have a yield strength greater than $50,000$ psi and a $\backslash \%$ elongation of at least $10\backslash \%.$ What range of final thicknesses must be obtained? $($See Figure $825.)$

Figure $8-25.$ The effect of percent cold work on the properties of a $\backslash (\backslash$mathrm$\{$Cu$\}-30\backslash \%\backslash$mathrm$\{$Zn$\}\backslash )$ brass.