70 Kg Is Hung from a Steel Wire of Diameter

Short Answer

7.0 kg is hung from a steel wire of diameter 0.75 mm and length 2.5 meters.
(S = 8.2 × 10¹⁰ N/m²; Y = 20 × 10¹⁰ N/m²)
(a) By how much does the wire stretch?
(b) If the wire diameter were doubled, what would be the stretch?