Find the minimumdiameter of a steel wire(young modulus=2 x 10^11 N/m^2) 18.0 m long that elongates no more tha?

Find the minimumdiameter of a steel wire(young modulus=2 x 10^11 N/m^2) 18.0 m long that elongates no more than 9.00 mm when a load of 380 kg us hung on its lower end.(b) if the elastic limit (maximum stress within elastic region) for this steel is 3 x 10^8 N/m^2 ,does permanent deformation occur with this load ?