$$\text { A composite beam is made up of a } 200 \mathrm {~mm} \times 300 \mathrm {~mm} \text { core } \left( E _ { c } = 14 \mathrm { GPa } \right) \text { and an exterior cover sheet }$$ $\left( 300 \mathrm {~mm} \times 12 \mathrm {~mm} , E _ { e } = 100 \mathrm { GPa } \right)$ on each side. Allowable stresses in core and exterior sheets are $9.5 \mathrm { MPa }$ and $140 \mathrm { MPa }$, respectively. The ratio of the maximum permissible bending moment about the $z$ axis to that about the $y$ axis is most nearly:

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The Answer of $$\text { A composite beam is made up of a } 200 \mathrm {~mm} \times 300 \mathrm {~mm} \text { core } \left( E _ { c } = 14 \mathrm { GPa } \right) \text { and an exterior cover sheet }$$ $\left( 300 \mathrm {~mm} \times 12 \mathrm {~mm} , E _ { e } = 100 \mathrm { GPa } \right)$ on each side. Allowable stresses in core and exterior sheets are $9.5 \mathrm { MPa }$ and $140 \mathrm { MPa }$, respectively. The ratio of the maximum permissible bending moment about the $z$ axis to that about the $y$ axis is most nearly:

(300 mm×12 mm,Ee=100GPa)\left( 300 \mathrm {~mm} \times 12 \mathrm {~mm} , E _ { e } = 100 \mathrm { GPa } \right)(300 mm×12 mm,Ee​=100GPa)

$\left( 300 \mathrm {~mm} \times 12 \mathrm {~mm} , E _ { e } = 100 \mathrm { GPa } \right)$