Answer:
a) 70.29 %
b) 37%
Explanation:
percent reduction can be found from:
PR = 100*(Ï€(do/2)^2-Ï€(df/2)^2)/Ï€(do/2)^2
   = 100*(π(11.34/2)^2-π(6.21/2)^2)/π(11.34/2)^2
   =70.29 %
percent elongation can be found from:
EL =L_f - Lo/Lo*100
  = (73.17 -53.3/53.3)*100
  = 37%