1In this problem use Y= stress/ strain.
Stress= deforming force/ area
Deforming force= weight of the body - upthrust of oil
upthrust = weight of displaced oil =vol of displaced oil x density x 'g'
Wt. of the body given in kgwt so upthrust = vol x density of oil in kg-wt.
vol of oil displacd = vol of solid.
Cross Sectional Area of wire can be calculated from the diameter given
Strain = change in length / initial length
Since Y is given so you will be able to calculate now