two wires of equal length and cross sectional area are suspended vertically. Their young modulii are Y1 and Y2 respectively. The equivalent young's modulii will be

If two wires of equal length, L and equal area of cross section, A are suspended vertically with Young modulii Y₁ and Y₂.
Let the Force be F then
Equivalent young modulus, Y = $\frac{Y_1+Y_2}{2}$
because all the parameter's are same and l i.e. stretching will be average value of stretching in wires.