An aluminium wire and a steel wire of the same length and cross section are joined end to end. The composite wire is hung from a rigid support and a load is suspended from the free end. If the increase in length of the composite wire is 1.35 mm, find the ratio of the i) stress in the two wires and ii) strains in the two wires. 

$\left({\mathrm{Y}}_{\mathrm{AI}}=7\times {10}^{10}{\mathrm{Nm}}^{-2}, {\mathrm{Y}}_{\mathrm{steel}}=2\times {10}^{11}{\mathrm{Nm}}^{-2}\right)$