http://i45.tinypic.com/2wburdd.jpg

member 1 is exponential of lambda=1 X1~exp(3)

member 2 is U(2,4) X2~U(2,4)

member 3 works 3 hours and then dont work at all

X3=1 for t<3

X3=0 for t>3

i developed it at much as i could

i dont know how to continue from this point

to find the formula