An iron rod of length 50 cm is jointed at an end to an aluminium rod of length 100 cm. All measurements refer to `20^(@) C`. The coefficients of linear expansion of iron and aluminium are `12xx 10^(-6) //^(@) C and 24 xx 10^(-6)//^(@) C`. Respectively. The average coefficient of composite system is

Options

A. `36 xx 10^(-6)//^(@) C`
B. `12 xx 10^(-6)//^(@) C`
C. `20 xx 10^(-6)//^(@) C`
D. `48 xx 10^(-6)//^(@) C`

Answer

C