Answer:
% reduction in area==PR=0.734=73.4%
% elongation=EL=0.42=42%
Explanation:
given do=12.8 mm
df=6.60
Lf=72.4 mm
Lo=50.8 mm
% reduction in area=(([tex]\pi[/tex]*(do/2)^2)-([tex]\pi[/tex]*(df/2)^2)))/[tex]\pi[/tex]*(do/2)^2
substitute values
% reduction in area=73.4%
% elongation=EL=((Lf-Lo)/Lo))*100
% elongation=((72.4-50. 8)/50.8)*100=42%