Question 1139142
Look at probability they don't pass any, which is 0.2*0.25*0.4=0.02
and probability they pass one, which is 0.8*0.25*0.4=0.08 or 0.2*0.75*0.4=0.06 or 0.2*0.25*0.6=0.03
These probabilities add to 0.19

Therefore at least two is the complement or 0.81