P(X= 1)= 1/5

p(X = 2)=(4/5)( 1/4)= 1/5

p(X = 3)=(4/5)(3/4)( 1/3)= 1/5

p(X = 4)=(4/5)(3/4)(2/3)( 1/2)= 1/5

p(X = 5)=(4/5)(3/4)(2/3)( 1/2) 1 = 1/5

EX =[P(X = 1)+P(X = 2)+P(X = 3)+P(X = 4)+P(X = 5)]/5